conlang: updated rustfmt

Plus it was more annoying than this is.

.cargo/config.toml

@@ -0,0 +1,2 @@
+[registries.soft-fish]
+index = "https://git.soft.fish/j/_cargo-index.git"

.gitignore

@@ -1,3 +1,13 @@
+
+# Visual Studio Code config
+.vscode
+
+# Rust
 **/Cargo.lock
 target
+
+# Symbol table dump?
+typeck-table.ron
+
+# Pest files generated by Grammatical
 *.p*st

Cargo.toml

@@ -1,20 +1,24 @@
 [workspace]
 members = [
-    "cl-repl",
-    "cl-typeck",
-    "cl-interpret",
-    "cl-structures",
-    "cl-token",
-    "cl-ast",
-    "cl-parser",
-    "cl-lexer",
+    "compiler/cl-repl",
+    "compiler/cl-typeck",
+    "compiler/cl-embed",
+    "compiler/cl-interpret",
+    "compiler/cl-structures",
+    "compiler/cl-token",
+    "compiler/cl-ast",
+    "compiler/cl-parser",
+    "compiler/cl-lexer",
 ]
 resolver = "2"
 
 [workspace.package]
 repository = "https://git.soft.fish/j/Conlang"
-version = "0.0.5"
+version = "0.0.10"
 authors = ["John Breaux <j@soft.fish>"]
-edition = "2021"
+edition = "2024"
 license = "MIT"
 publish = ["soft-fish"]
+
+[profile.dev]
+opt-level = 1

cl-ast/src/ast_impl.rs

@@ -1,643 +0,0 @@
-//! Implementations of AST nodes and traits
-use super::*;
-
-mod display {
-    //! Implements [Display] for [AST](super::super) Types
-    use super::*;
-    pub use delimiters::*;
-    use std::{
-        borrow::Borrow,
-        fmt::{Display, Write},
-    };
-    mod delimiters {
-        #![allow(dead_code)]
-        #[derive(Clone, Copy, Debug)]
-        pub struct Delimiters<'t> {
-            pub open: &'t str,
-            pub close: &'t str,
-        }
-        /// Delimits with braces decorated with spaces  `" {n"`, ..., `"\n}"`
-        pub const SPACED_BRACES: Delimiters = Delimiters { open: " {\n", close: "\n}" };
-        /// Delimits with braces on separate lines `{\n`, ..., `\n}`
-        pub const BRACES: Delimiters = Delimiters { open: "{\n", close: "\n}" };
-        /// Delimits with parentheses on separate lines `{\n`, ..., `\n}`
-        pub const PARENS: Delimiters = Delimiters { open: "(\n", close: "\n)" };
-        /// Delimits with square brackets on separate lines `{\n`, ..., `\n}`
-        pub const SQUARE: Delimiters = Delimiters { open: "[\n", close: "\n]" };
-        /// Delimits with braces on the same line `{ `, ..., ` }`
-        pub const INLINE_BRACES: Delimiters = Delimiters { open: "{ ", close: " }" };
-        /// Delimits with parentheses on the same line `( `, ..., ` )`
-        pub const INLINE_PARENS: Delimiters = Delimiters { open: "(", close: ")" };
-        /// Delimits with square brackets on the same line `[ `, ..., ` ]`
-        pub const INLINE_SQUARE: Delimiters = Delimiters { open: "[", close: "]" };
-    }
-    fn delimit<'a>(
-        func: impl Fn(&mut std::fmt::Formatter<'_>) -> std::fmt::Result + 'a,
-        delim: Delimiters<'a>,
-    ) -> impl Fn(&mut std::fmt::Formatter<'_>) -> std::fmt::Result + 'a {
-        move |f| {
-            write!(f, "{}", delim.open)?;
-            func(f)?;
-            write!(f, "{}", delim.close)
-        }
-    }
-    fn separate<'iterable, I>(
-        iterable: &'iterable [I],
-        sep: impl Display + 'iterable,
-    ) -> impl Fn(&mut std::fmt::Formatter<'_>) -> std::fmt::Result + 'iterable
-    where
-        I: Display,
-    {
-        move |f| {
-            for (idx, item) in iterable.iter().enumerate() {
-                if idx > 0 {
-                    write!(f, "{sep}")?;
-                }
-                item.fmt(f)?;
-            }
-            Ok(())
-        }
-    }
-
-    impl Display for Mutability {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            match self {
-                Mutability::Not => Ok(()),
-                Mutability::Mut => "mut ".fmt(f),
-            }
-        }
-    }
-    impl Display for Visibility {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            match self {
-                Visibility::Private => Ok(()),
-                Visibility::Public => "pub ".fmt(f),
-            }
-        }
-    }
-
-    impl Display for File {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            separate(&self.items, "\n")(f)
-        }
-    }
-
-    impl Display for Attrs {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { meta } = self;
-            if meta.is_empty() {
-                return Ok(());
-            }
-            "#".fmt(f)?;
-            delimit(separate(meta, ", "), INLINE_SQUARE)(f)?;
-            "\n".fmt(f)
-        }
-    }
-    impl Display for Meta {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { name, kind } = self;
-            write!(f, "{name}{kind}")
-        }
-    }
-    impl Display for MetaKind {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            match self {
-                MetaKind::Plain => Ok(()),
-                MetaKind::Equals(v) => write!(f, " = {v}"),
-                MetaKind::Func(args) => delimit(separate(args, ", "), INLINE_PARENS)(f),
-            }
-        }
-    }
-
-    impl Display for Item {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { extents: _, attrs, vis, kind } = self;
-            attrs.fmt(f)?;
-            vis.fmt(f)?;
-            match kind {
-                ItemKind::Alias(v) => v.fmt(f),
-                ItemKind::Const(v) => v.fmt(f),
-                ItemKind::Static(v) => v.fmt(f),
-                ItemKind::Module(v) => v.fmt(f),
-                ItemKind::Function(v) => v.fmt(f),
-                ItemKind::Struct(v) => v.fmt(f),
-                ItemKind::Enum(v) => v.fmt(f),
-                ItemKind::Impl(v) => v.fmt(f),
-            }
-        }
-    }
-    impl Display for Alias {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { to, from } = self;
-            match from {
-                Some(from) => write!(f, "type {to} = {from};"),
-                None => write!(f, "type {to};"),
-            }
-        }
-    }
-    impl Display for Const {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { name, ty, init } = self;
-            write!(f, "const {name}: {ty} = {init}")
-        }
-    }
-    impl Display for Static {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { mutable, name, ty, init } = self;
-            write!(f, "static {mutable}{name}: {ty} = {init}")
-        }
-    }
-    impl Display for Module {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { name, kind } = self;
-            write!(f, "mod {name}{kind}")
-        }
-    }
-    impl Display for ModuleKind {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            match self {
-                ModuleKind::Inline(items) => {
-                    ' '.fmt(f)?;
-                    delimit(|f| items.fmt(f), BRACES)(f)
-                }
-                ModuleKind::Outline => ';'.fmt(f),
-            }
-        }
-    }
-    impl Display for Function {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { name, args, body, rety } = self;
-            write!(f, "fn {name} ")?;
-            delimit(separate(args, ", "), INLINE_PARENS)(f)?;
-            if let Some(rety) = rety {
-                write!(f, " -> {rety}")?;
-            }
-            match body {
-                Some(body) => write!(f, " {body}"),
-                None => ';'.fmt(f),
-            }
-        }
-    }
-    impl Display for Param {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { mutability, name, ty } = self;
-            write!(f, "{mutability}{name}: {ty}")
-        }
-    }
-    impl Display for Struct {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { name, kind } = self;
-            write!(f, "struct {name}{kind}")
-        }
-    }
-    impl Display for StructKind {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            match self {
-                StructKind::Empty => ';'.fmt(f),
-                StructKind::Tuple(v) => delimit(separate(v, ", "), INLINE_PARENS)(f),
-                StructKind::Struct(v) => delimit(separate(v, ",\n"), SPACED_BRACES)(f),
-            }
-        }
-    }
-    impl Display for StructMember {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { vis, name, ty } = self;
-            write!(f, "{vis}{name}: {ty}")
-        }
-    }
-    impl Display for Enum {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { name, kind } = self;
-            write!(f, "enum {name}{kind}")
-        }
-    }
-    impl Display for EnumKind {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            match self {
-                EnumKind::NoVariants => ';'.fmt(f),
-                EnumKind::Variants(v) => delimit(separate(v, ",\n"), SPACED_BRACES)(f),
-            }
-        }
-    }
-    impl Display for Variant {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { name, kind } = self;
-            write!(f, "{name}{kind}")
-        }
-    }
-    impl Display for VariantKind {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            match self {
-                VariantKind::Plain => Ok(()),
-                VariantKind::CLike(n) => write!(f, " = {n}"),
-                VariantKind::Tuple(v) => delimit(separate(v, ", "), INLINE_PARENS)(f),
-                VariantKind::Struct(v) => delimit(separate(v, ", "), INLINE_BRACES)(f),
-            }
-        }
-    }
-    impl Display for Impl {
-        fn fmt(&self, _f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            todo!("impl Display for Impl")
-        }
-    }
-
-    impl Display for Ty {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            match &self.kind {
-                TyKind::Never => "!".fmt(f),
-                TyKind::Empty => "()".fmt(f),
-                TyKind::SelfTy => "Self".fmt(f),
-                TyKind::Path(v) => v.fmt(f),
-                TyKind::Tuple(v) => v.fmt(f),
-                TyKind::Ref(v) => v.fmt(f),
-                TyKind::Fn(v) => v.fmt(f),
-            }
-        }
-    }
-    impl Display for TyTuple {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            delimit(separate(&self.types, ", "), INLINE_PARENS)(f)
-        }
-    }
-    impl Display for TyRef {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { count: _, to } = self;
-            for _ in 0..self.count {
-                f.write_char('&')?;
-            }
-            write!(f, "{to}")
-        }
-    }
-    impl Display for TyFn {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { args, rety } = self;
-            write!(f, "fn {args}")?;
-            match rety {
-                Some(v) => write!(f, " -> {v}"),
-                None => Ok(()),
-            }
-        }
-    }
-
-    impl Display for Stmt {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Stmt { extents: _, kind, semi } = self;
-            match kind {
-                StmtKind::Empty => Ok(()),
-                StmtKind::Local(v) => v.fmt(f),
-                StmtKind::Item(v) => v.fmt(f),
-                StmtKind::Expr(v) => v.fmt(f),
-            }?;
-            match semi {
-                Semi::Terminated => ';'.fmt(f),
-                Semi::Unterminated => Ok(()),
-            }
-        }
-    }
-    impl Display for Let {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { mutable, name, ty, init } = self;
-            write!(f, "let {mutable}{name}")?;
-            if let Some(value) = ty {
-                write!(f, ": {value}")?;
-            }
-            if let Some(value) = init {
-                write!(f, " = {value}")?;
-            }
-            Ok(())
-        }
-    }
-
-    impl Display for Expr {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            self.kind.fmt(f)
-        }
-    }
-    impl Display for ExprKind {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            match self {
-                ExprKind::Assign(v) => v.fmt(f),
-                ExprKind::Binary(v) => v.fmt(f),
-                ExprKind::Unary(v) => v.fmt(f),
-                ExprKind::Index(v) => v.fmt(f),
-                ExprKind::Path(v) => v.fmt(f),
-                ExprKind::Literal(v) => v.fmt(f),
-                ExprKind::Array(v) => v.fmt(f),
-                ExprKind::ArrayRep(v) => v.fmt(f),
-                ExprKind::AddrOf(v) => v.fmt(f),
-                ExprKind::Block(v) => v.fmt(f),
-                ExprKind::Empty => "()".fmt(f),
-                ExprKind::Group(v) => v.fmt(f),
-                ExprKind::Tuple(v) => v.fmt(f),
-                ExprKind::While(v) => v.fmt(f),
-                ExprKind::If(v) => v.fmt(f),
-                ExprKind::For(v) => v.fmt(f),
-                ExprKind::Break(v) => v.fmt(f),
-                ExprKind::Return(v) => v.fmt(f),
-                ExprKind::Continue(_) => "continue".fmt(f),
-            }
-        }
-    }
-    impl Display for Assign {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { kind, parts } = self;
-            write!(f, "{} {kind} {}", parts.0, parts.1)
-        }
-    }
-    impl Display for AssignKind {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            match self {
-                AssignKind::Plain => "=",
-                AssignKind::Mul => "*=",
-                AssignKind::Div => "/=",
-                AssignKind::Rem => "%=",
-                AssignKind::Add => "+=",
-                AssignKind::Sub => "-=",
-                AssignKind::And => "&=",
-                AssignKind::Or => "|=",
-                AssignKind::Xor => "^=",
-                AssignKind::Shl => "<<=",
-                AssignKind::Shr => ">>=",
-            }
-            .fmt(f)
-        }
-    }
-    impl Display for Binary {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { kind, parts } = self;
-            let (head, tail) = parts.borrow();
-            match kind {
-                BinaryKind::Dot => write!(f, "{head}{kind}{tail}"),
-                BinaryKind::Call => write!(f, "{head}{tail}"),
-                _ => write!(f, "{head} {kind} {tail}"),
-            }
-        }
-    }
-    impl Display for BinaryKind {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            match self {
-                BinaryKind::Lt => "<",
-                BinaryKind::LtEq => "<=",
-                BinaryKind::Equal => "==",
-                BinaryKind::NotEq => "!=",
-                BinaryKind::GtEq => ">=",
-                BinaryKind::Gt => ">",
-                BinaryKind::RangeExc => "..",
-                BinaryKind::RangeInc => "..=",
-                BinaryKind::LogAnd => "&&",
-                BinaryKind::LogOr => "||",
-                BinaryKind::LogXor => "^^",
-                BinaryKind::BitAnd => "&",
-                BinaryKind::BitOr => "|",
-                BinaryKind::BitXor => "^",
-                BinaryKind::Shl => "<<",
-                BinaryKind::Shr => ">>",
-                BinaryKind::Add => "+",
-                BinaryKind::Sub => "-",
-                BinaryKind::Mul => "*",
-                BinaryKind::Div => "/",
-                BinaryKind::Rem => "%",
-                BinaryKind::Dot => ".",
-                BinaryKind::Call => "()",
-            }
-            .fmt(f)
-        }
-    }
-    impl Display for Unary {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { kind, tail } = self;
-            write!(f, "{kind}{tail}")
-        }
-    }
-    impl Display for UnaryKind {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            match self {
-                UnaryKind::Deref => "*",
-                UnaryKind::Neg => "-",
-                UnaryKind::Not => "!",
-                UnaryKind::At => "@",
-                UnaryKind::Tilde => "~",
-            }
-            .fmt(f)
-        }
-    }
-    impl Display for Tuple {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            delimit(separate(&self.exprs, ", "), INLINE_PARENS)(f)
-        }
-    }
-    impl Display for Index {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { head, indices } = self;
-            write!(f, "{head}")?;
-            for indices in indices {
-                indices.fmt(f)?;
-            }
-            Ok(())
-        }
-    }
-    impl Display for Path {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { absolute, parts } = self;
-            if *absolute {
-                "::".fmt(f)?;
-            }
-            separate(parts, "::")(f)
-        }
-    }
-    impl Display for PathPart {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            match self {
-                PathPart::SuperKw => "super".fmt(f),
-                PathPart::SelfKw => "self".fmt(f),
-                PathPart::Ident(id) => id.fmt(f),
-            }
-        }
-    }
-    impl Display for Identifier {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            self.0.fmt(f)
-        }
-    }
-    impl Display for Literal {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            match self {
-                Literal::Bool(v) => v.fmt(f),
-                Literal::Char(v) => write!(f, "'{v}'"),
-                Literal::Int(v) => v.fmt(f),
-                Literal::String(v) => write!(f, "\"{v}\""),
-            }
-        }
-    }
-    impl Display for Array {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            delimit(separate(&self.values, ", "), INLINE_SQUARE)(f)
-        }
-    }
-    impl Display for ArrayRep {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { value, repeat } = self;
-            write!(f, "[{value}; {repeat}]")
-        }
-    }
-    impl Display for AddrOf {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { count, mutable, expr } = self;
-            for _ in 0..*count {
-                f.write_char('&')?;
-            }
-            write!(f, "{mutable}{expr}")
-        }
-    }
-    impl Display for Block {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            delimit(separate(&self.stmts, "\n"), BRACES)(f)
-        }
-    }
-    impl Display for Group {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            write!(f, "({})", self.expr)
-        }
-    }
-    impl Display for While {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { cond, pass, fail } = self;
-            write!(f, "while {cond} {pass}{fail}")
-        }
-    }
-    impl Display for If {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { cond, pass, fail } = self;
-            write!(f, "if {cond} {pass}{fail}")
-        }
-    }
-    impl Display for For {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { bind, cond, pass, fail } = self;
-            write!(f, "for {bind} in {cond} {pass}{fail}")
-        }
-    }
-    impl Display for Else {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            match &self.body {
-                Some(body) => write!(f, " else {body}"),
-                _ => Ok(()),
-            }
-        }
-    }
-    impl Display for Break {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            write!(f, "break")?;
-            match &self.body {
-                Some(body) => write!(f, " {body}"),
-                _ => Ok(()),
-            }
-        }
-    }
-    impl Display for Return {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            write!(f, "return")?;
-            match &self.body {
-                Some(body) => write!(f, " {body}"),
-                _ => Ok(()),
-            }
-        }
-    }
-}
-
-mod convert {
-    //! Converts between major enums and enum variants
-    use super::*;
-
-    impl<T: AsRef<str>> From<T> for Identifier {
-        fn from(value: T) -> Self {
-            Identifier(value.as_ref().into())
-        }
-    }
-
-    macro impl_from ($(impl From for $T:ty {$($from:ty => $to:expr),*$(,)?})*) {$($(
-        impl From<$from> for $T {
-            fn from(value: $from) -> Self {
-                $to(value.into()) // Uses *tuple constructor*
-            }
-        }
-        impl From<Box<$from>> for $T {
-            fn from(value: Box<$from>) -> Self {
-                $to((*value).into())
-            }
-        }
-    )*)*}
-
-    impl_from! {
-        impl From for ItemKind {
-            Alias => ItemKind::Alias,
-            Const => ItemKind::Const,
-            Static => ItemKind::Static,
-            Module => ItemKind::Module,
-            Function => ItemKind::Function,
-            Struct => ItemKind::Struct,
-            Enum => ItemKind::Enum,
-            Impl => ItemKind::Impl,
-        }
-        impl From for StructKind {
-            Vec<Ty> => StructKind::Tuple,
-            // TODO: Struct members in struct
-        }
-        impl From for EnumKind {
-            Vec<Variant> => EnumKind::Variants,
-        }
-        impl From for VariantKind {
-            u128 => VariantKind::CLike,
-            Vec<Ty> => VariantKind::Tuple,
-            // TODO: enum struct variants
-        }
-        impl From for TyKind {
-            Path => TyKind::Path,
-            TyTuple => TyKind::Tuple,
-            TyRef => TyKind::Ref,
-            TyFn => TyKind::Fn,
-        }
-        impl From for StmtKind {
-            Let => StmtKind::Local,
-            Item => StmtKind::Item,
-            Expr => StmtKind::Expr,
-        }
-        impl From for ExprKind {
-            Assign => ExprKind::Assign,
-            Binary => ExprKind::Binary,
-            Unary => ExprKind::Unary,
-            Index => ExprKind::Index,
-            Path => ExprKind::Path,
-            Literal => ExprKind::Literal,
-            Array => ExprKind::Array,
-            ArrayRep => ExprKind::ArrayRep,
-            AddrOf => ExprKind::AddrOf,
-            Block => ExprKind::Block,
-            Group => ExprKind::Group,
-            Tuple => ExprKind::Tuple,
-            While => ExprKind::While,
-            If => ExprKind::If,
-            For => ExprKind::For,
-            Break => ExprKind::Break,
-            Return => ExprKind::Return,
-            Continue => ExprKind::Continue,
-        }
-        impl From for Literal {
-            bool => Literal::Bool,
-            char => Literal::Char,
-            u128 => Literal::Int,
-            String => Literal::String,
-        }
-    }
-
-    impl From<Option<Expr>> for Else {
-        fn from(value: Option<Expr>) -> Self {
-            Self { body: value.map(Into::into) }
-        }
-    }
-    impl From<Expr> for Else {
-        fn from(value: Expr) -> Self {
-            Self { body: Some(value.into()) }
-        }
-    }
-}

cl-ast/src/format.rs

@@ -1,106 +0,0 @@
-use std::{
-    fmt::{Result as FmtResult, Write as FmtWrite},
-    io::{Result as IoResult, Write as IoWrite},
-};
-
-/// Trait which adds a function to [fmt Writers](FmtWrite) to turn them into [Prettifier]
-pub trait FmtPretty: FmtWrite {
-    /// Indents code according to the number of matched curly braces
-    fn pretty(self) -> Prettifier<'static, Self>
-    where Self: Sized {
-        Prettifier::new(self)
-    }
-}
-/// Trait which adds a function to [io Writers](IoWrite) to turn them into [Prettifier]
-pub trait IoPretty: IoWrite {
-    /// Indents code according to the number of matched curly braces
-    fn pretty(self) -> Prettifier<'static, Self>
-    where Self: Sized;
-}
-impl<W: FmtWrite> FmtPretty for W {}
-impl<W: IoWrite> IoPretty for W {
-    fn pretty(self) -> Prettifier<'static, Self> {
-        Prettifier::new(self)
-    }
-}
-
-/// Intercepts calls to either [std::io::Write] or [std::fmt::Write],
-/// and inserts indentation between matched parentheses
-pub struct Prettifier<'i, T: ?Sized> {
-    level: isize,
-    indent: &'i str,
-    writer: T,
-}
-
-impl<'i, W> Prettifier<'i, W> {
-    pub fn new(writer: W) -> Self {
-        Self { level: 0, indent: "    ", writer }
-    }
-    pub fn with_indent(indent: &'i str, writer: W) -> Self {
-        Self { level: 0, indent, writer }
-    }
-}
-
-impl<'i, W: FmtWrite> Prettifier<'i, W> {
-    #[inline]
-    fn fmt_write_indentation(&mut self) -> FmtResult {
-        let Self { level, indent, writer } = self;
-        for _ in 0..*level {
-            writer.write_str(indent)?;
-        }
-        Ok(())
-    }
-}
-impl<'i, W: IoWrite> Prettifier<'i, W> {
-    pub fn io_write_indentation(&mut self) -> IoResult<usize> {
-        let Self { level, indent, writer } = self;
-        let mut count = 0;
-        for _ in 0..*level {
-            count += writer.write(indent.as_bytes())?;
-        }
-        Ok(count)
-    }
-}
-
-impl<'i, W: FmtWrite> FmtWrite for Prettifier<'i, W> {
-    fn write_str(&mut self, s: &str) -> FmtResult {
-        for s in s.split_inclusive(['{', '}']) {
-            match s.as_bytes().last() {
-                Some(b'{') => self.level += 1,
-                Some(b'}') => self.level -= 1,
-                _ => (),
-            }
-            for s in s.split_inclusive('\n') {
-                self.writer.write_str(s)?;
-                if let Some(b'\n') = s.as_bytes().last() {
-                    self.fmt_write_indentation()?;
-                }
-            }
-        }
-        Ok(())
-    }
-}
-
-impl<'i, W: IoWrite> IoWrite for Prettifier<'i, W> {
-    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
-        let mut size = 0;
-        for buf in buf.split_inclusive(|b| b"{}".contains(b)) {
-            match buf.last() {
-                Some(b'{') => self.level += 1,
-                Some(b'}') => self.level -= 1,
-                _ => (),
-            }
-            for buf in buf.split_inclusive(|b| b'\n' == *b) {
-                size += self.writer.write(buf)?;
-                if let Some(b'\n') = buf.last() {
-                    self.io_write_indentation()?;
-                }
-            }
-        }
-        Ok(size)
-    }
-
-    fn flush(&mut self) -> std::io::Result<()> {
-        self.writer.flush()
-    }
-}

cl-ast/src/lib.rs

@@ -1,539 +0,0 @@
-//! # The Abstract Syntax Tree
-//! Contains definitions of Conlang AST Nodes.
-//!
-//! # Notable nodes
-//! - [Item] and [ItemKind]: Top-level constructs
-//! - [Stmt] and [StmtKind]: Statements
-//! - [Expr] and [ExprKind]: Expressions
-//!   - [Assign], [Binary], and [Unary] expressions
-//!   - [AssignKind], [BinaryKind], and [UnaryKind] operators
-//! - [Ty] and [TyKind]: Type qualifiers
-//! - [Path]: Path expressions
-#![warn(clippy::all)]
-#![feature(decl_macro)]
-
-use cl_structures::span::*;
-
-pub mod ast_impl;
-pub mod format;
-
-/// Whether a binding ([Static] or [Let]) or reference is mutable or not
-#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
-pub enum Mutability {
-    #[default]
-    Not,
-    Mut,
-}
-
-/// Whether an [Item] is visible outside of the current [Module]
-#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
-pub enum Visibility {
-    #[default]
-    Private,
-    Public,
-}
-
-/// A list of [Item]s
-#[derive(Clone, Debug, Default, PartialEq, Eq)]
-pub struct File {
-    pub items: Vec<Item>,
-}
-
-// Metadata decorators
-#[derive(Clone, Debug, Default, PartialEq, Eq)]
-pub struct Attrs {
-    pub meta: Vec<Meta>,
-}
-
-/// A metadata decorator
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Meta {
-    pub name: Identifier,
-    pub kind: MetaKind,
-}
-
-/// Information attached to [Meta]data
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub enum MetaKind {
-    Plain,
-    Equals(Literal),
-    Func(Vec<Literal>),
-}
-
-// Items
-/// Anything that can appear at the top level of a [File]
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Item {
-    pub extents: Span,
-    pub attrs: Attrs,
-    pub vis: Visibility,
-    pub kind: ItemKind,
-}
-
-/// What kind of [Item] is this?
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub enum ItemKind {
-    // TODO: Import declaration ("use") item
-    // TODO: Trait declaration ("trait") item?
-    /// A [module](Module)
-    Module(Module),
-    /// A [type alias](Alias)
-    Alias(Alias),
-    /// An [enumerated type](Enum), with a discriminant and optional data
-    Enum(Enum),
-    /// A [structure](Struct)
-    Struct(Struct),
-    /// A [constant](Const)
-    Const(Const),
-    /// A [static](Static) variable
-    Static(Static),
-    /// A [function definition](Function)
-    Function(Function),
-    /// An [implementation](Impl)
-    Impl(Impl),
-}
-
-/// An alias to another [Ty]
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Alias {
-    pub to: Identifier,
-    pub from: Option<Box<Ty>>,
-}
-
-/// A compile-time constant
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Const {
-    pub name: Identifier,
-    pub ty: Box<Ty>,
-    pub init: Box<Expr>,
-}
-
-/// A `static` variable
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Static {
-    pub mutable: Mutability,
-    pub name: Identifier,
-    pub ty: Box<Ty>,
-    pub init: Box<Expr>,
-}
-
-/// An ordered collection of [Items](Item)
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Module {
-    pub name: Identifier,
-    pub kind: ModuleKind,
-}
-
-/// The contents of a [Module], if they're in the same file
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub enum ModuleKind {
-    Inline(File),
-    Outline,
-}
-
-/// Code, and the interface to that code
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Function {
-    pub name: Identifier,
-    pub args: Vec<Param>,
-    pub body: Option<Block>,
-    pub rety: Option<Box<Ty>>,
-}
-
-/// A single parameter for a [Function]
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Param {
-    pub mutability: Mutability,
-    pub name: Identifier,
-    pub ty: Box<Ty>,
-}
-
-/// A user-defined product type
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Struct {
-    pub name: Identifier,
-    pub kind: StructKind,
-}
-
-/// Either a [Struct]'s [StructMember]s or tuple [Ty]pes, if present.
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub enum StructKind {
-    Empty,
-    Tuple(Vec<Ty>),
-    Struct(Vec<StructMember>),
-}
-
-/// The [Visibility], [Identifier], and [Ty]pe of a single [Struct] member
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct StructMember {
-    pub vis: Visibility,
-    pub name: Identifier,
-    pub ty: Ty,
-}
-
-/// A user-defined sum type
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Enum {
-    pub name: Identifier,
-    pub kind: EnumKind,
-}
-
-/// An [Enum]'s [Variant]s, if it has a variant block
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub enum EnumKind {
-    /// Represents an enum with no variants
-    NoVariants,
-    Variants(Vec<Variant>),
-}
-
-/// A single [Enum] variant
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Variant {
-    pub name: Identifier,
-    pub kind: VariantKind,
-}
-
-/// Whether the [Variant] has a C-like constant value, a tuple, or [StructMember]s
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub enum VariantKind {
-    Plain,
-    CLike(u128),
-    Tuple(Vec<Ty>),
-    Struct(Vec<StructMember>),
-}
-
-/// Sub-[items](Item) (associated functions, etc.) for a [Ty]
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Impl {
-    pub target: Ty,
-    pub body: Vec<Item>,
-}
-
-// TODO: `impl` Trait for <Target> { }
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub enum ImplKind {
-    Type(Box<Ty>),
-    Trait { impl_trait: Path, for_type: Box<Ty> },
-}
-
-/// A type expression
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Ty {
-    pub extents: Span,
-    pub kind: TyKind,
-}
-
-/// Information about a [Ty]pe expression
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub enum TyKind {
-    Never,
-    Empty,
-    SelfTy,
-    Path(Path),
-    Tuple(TyTuple),
-    Ref(TyRef),
-    Fn(TyFn),
-}
-
-/// A tuple of [Ty]pes
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct TyTuple {
-    pub types: Vec<Ty>,
-}
-
-/// A [Ty]pe-reference expression as (number of `&`, [Path])
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct TyRef {
-    pub count: u16,
-    pub to: Path,
-}
-
-/// The args and return value for a function pointer [Ty]pe
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct TyFn {
-    pub args: TyTuple,
-    pub rety: Option<Box<Ty>>,
-}
-
-/// A path to an [Item] in the [Module] tree
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Path {
-    pub absolute: bool,
-    pub parts: Vec<PathPart>,
-}
-
-/// A single component of a [Path]
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub enum PathPart {
-    SuperKw,
-    SelfKw,
-    Ident(Identifier),
-}
-
-// TODO: Capture token?
-/// A name
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Identifier(pub String);
-
-/// An abstract statement, and associated metadata
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Stmt {
-    pub extents: Span,
-    pub kind: StmtKind,
-    pub semi: Semi,
-}
-
-/// Whether or not a [Stmt] is followed by a semicolon
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub enum Semi {
-    Terminated,
-    Unterminated,
-}
-
-/// Whether the [Stmt] is a [Let], [Item], or [Expr] statement
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub enum StmtKind {
-    Empty,
-    Local(Let),
-    Item(Box<Item>),
-    Expr(Box<Expr>),
-}
-
-/// A local variable declaration [Stmt]
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Let {
-    pub mutable: Mutability,
-    pub name: Identifier,
-    pub ty: Option<Box<Ty>>,
-    pub init: Option<Box<Expr>>,
-}
-
-/// An expression, the beating heart of the language
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Expr {
-    pub extents: Span,
-    pub kind: ExprKind,
-}
-
-/// Any of the different [Expr]essions
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub enum ExprKind {
-    /// An [Assign]ment expression: [`Expr`] ([`AssignKind`] [`Expr`])\+
-    Assign(Assign),
-    /// A [Binary] expression: [`Expr`] ([`BinaryKind`] [`Expr`])\+
-    Binary(Binary),
-    /// A [Unary] expression: [`UnaryKind`]\* [`Expr`]
-    Unary(Unary),
-    /// An Array [Index] expression: a[10, 20, 30]
-    Index(Index),
-    /// A [path expression](Path): `::`? [PathPart] (`::` [PathPart])*
-    Path(Path),
-    /// A [Literal]: 0x42, 1e123, 2.4, "Hello"
-    Literal(Literal),
-    /// An [Array] literal: `[` [`Expr`] (`,` [`Expr`])\* `]`
-    Array(Array),
-    /// An Array literal constructed with [repeat syntax](ArrayRep)
-    /// `[` [Expr] `;` [Literal] `]`
-    ArrayRep(ArrayRep),
-    /// An address-of expression: `&` `mut`? [`Expr`]
-    AddrOf(AddrOf),
-    /// A [Block] expression: `{` [`Stmt`]\* [`Expr`]? `}`
-    Block(Block),
-    /// An empty expression: `(` `)`
-    Empty,
-    /// A [Grouping](Group) expression `(` [`Expr`] `)`
-    Group(Group),
-    /// A [Tuple] expression: `(` [`Expr`] (`,` [`Expr`])+ `)`
-    Tuple(Tuple),
-    /// A [While] expression: `while` [`Expr`] [`Block`] [`Else`]?
-    While(While),
-    /// An [If] expression: `if` [`Expr`] [`Block`] [`Else`]?
-    If(If),
-    /// A [For] expression: `for` Pattern `in` [`Expr`] [`Block`] [`Else`]?
-    For(For),
-    /// A [Break] expression: `break` [`Expr`]?
-    Break(Break),
-    /// A [Return] expression `return` [`Expr`]?
-    Return(Return),
-    /// A continue expression: `continue`
-    Continue(Continue),
-}
-
-/// An [Assign]ment expression: [`Expr`] ([`AssignKind`] [`Expr`])\+
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Assign {
-    pub kind: AssignKind,
-    pub parts: Box<(ExprKind, ExprKind)>,
-}
-
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
-pub enum AssignKind {
-    /// Standard Assignment with no read-back
-    Plain,
-    And,
-    Or,
-    Xor,
-    Shl,
-    Shr,
-    Add,
-    Sub,
-    Mul,
-    Div,
-    Rem,
-}
-
-/// A [Binary] expression: [`Expr`] ([`BinaryKind`] [`Expr`])\+
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Binary {
-    pub kind: BinaryKind,
-    pub parts: Box<(ExprKind, ExprKind)>,
-}
-
-/// A [Binary] operator
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
-pub enum BinaryKind {
-    Lt,
-    LtEq,
-    Equal,
-    NotEq,
-    GtEq,
-    Gt,
-    RangeExc,
-    RangeInc,
-    LogAnd,
-    LogOr,
-    LogXor,
-    BitAnd,
-    BitOr,
-    BitXor,
-    Shl,
-    Shr,
-    Add,
-    Sub,
-    Mul,
-    Div,
-    Rem,
-    Dot,
-    Call,
-}
-
-/// A [Unary] expression: [`UnaryKind`]\* [`Expr`]
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Unary {
-    pub kind: UnaryKind,
-    pub tail: Box<ExprKind>,
-}
-
-/// A [Unary] operator
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
-pub enum UnaryKind {
-    Deref,
-    Neg,
-    Not,
-    /// Unused
-    At,
-    /// Unused
-    Tilde,
-}
-/// A repeated [Index] expression: a[10, 20, 30][40, 50, 60]
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Index {
-    pub head: Box<ExprKind>,
-    pub indices: Vec<Expr>,
-}
-
-/// A [Literal]: 0x42, 1e123, 2.4, "Hello"
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub enum Literal {
-    Bool(bool),
-    Char(char),
-    Int(u128),
-    String(String),
-}
-
-/// An [Array] literal: `[` [`Expr`] (`,` [`Expr`])\* `]`
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Array {
-    pub values: Vec<Expr>,
-}
-
-/// An Array literal constructed with [repeat syntax](ArrayRep)
-/// `[` [Expr] `;` [Literal] `]`
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct ArrayRep {
-    pub value: Box<ExprKind>,
-    pub repeat: Box<ExprKind>,
-}
-
-/// An address-of expression: `&` `mut`? [`Expr`]
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct AddrOf {
-    pub count: usize,
-    pub mutable: Mutability,
-    pub expr: Box<ExprKind>,
-}
-
-/// A [Block] expression: `{` [`Stmt`]\* [`Expr`]? `}`
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Block {
-    pub stmts: Vec<Stmt>,
-}
-
-/// A [Grouping](Group) expression `(` [`Expr`] `)`
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Group {
-    pub expr: Box<ExprKind>,
-}
-
-/// A [Tuple] expression: `(` [`Expr`] (`,` [`Expr`])+ `)`
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Tuple {
-    pub exprs: Vec<Expr>,
-}
-
-/// A [While] expression: `while` [`Expr`] [`Block`] [`Else`]?
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct While {
-    pub cond: Box<Expr>,
-    pub pass: Box<Block>,
-    pub fail: Else,
-}
-
-/// An [If] expression: `if` [`Expr`] [`Block`] [`Else`]?
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct If {
-    pub cond: Box<Expr>,
-    pub pass: Box<Block>,
-    pub fail: Else,
-}
-
-/// A [For] expression: `for` Pattern `in` [`Expr`] [`Block`] [`Else`]?
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct For {
-    pub bind: Identifier, // TODO: Patterns?
-    pub cond: Box<Expr>,
-    pub pass: Box<Block>,
-    pub fail: Else,
-}
-
-/// The (optional) `else` clause of a [While], [If], or [For] expression
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Else {
-    pub body: Option<Box<Expr>>,
-}
-
-/// A [Break] expression: `break` [`Expr`]?
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Break {
-    pub body: Option<Box<Expr>>,
-}
-
-/// A [Return] expression `return` [`Expr`]?
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Return {
-    pub body: Option<Box<Expr>>,
-}
-
-/// A continue expression: `continue`
-#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
-pub struct Continue;

cl-interpret/src/builtin.rs

@@ -1,239 +0,0 @@
-//! Implementations of built-in functions
-
-use super::{
-    env::Environment,
-    error::{Error, IResult},
-    temp_type_impl::ConValue,
-    BuiltIn, Callable,
-};
-use std::io::{stdout, Write};
-
-builtins! {
-    const MISC;
-    /// Unstable variadic print function
-    pub fn print<_, args> () -> IResult<ConValue> {
-        let mut out = stdout().lock();
-        for arg in args {
-            write!(out, "{arg}").ok();
-        }
-        writeln!(out).ok();
-        Ok(ConValue::Empty)
-    }
-    /// Prints the [Debug](std::fmt::Debug) version of the input values
-    pub fn dbg<_, args> () -> IResult<ConValue> {
-        let mut out = stdout().lock();
-        for arg in args {
-            writeln!(out, "{arg:?}").ok();
-        }
-        Ok(args.into())
-    }
-    /// Dumps info from the environment
-    pub fn dump<env, _>() -> IResult<ConValue> {
-        println!("{}", *env);
-        Ok(ConValue::Empty)
-    }
-}
-builtins! {
-    const BINARY;
-    /// Multiplication `a * b`
-    pub fn mul(lhs, rhs) -> IResult<ConValue> {
-        Ok(match (lhs, rhs) {
-            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a * b),
-            _ => Err(Error::TypeError)?
-        })
-    }
-    /// Division `a / b`
-    pub fn div(lhs, rhs) -> IResult<ConValue> {
-        Ok(match (lhs, rhs){
-            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a / b),
-            _ => Err(Error::TypeError)?
-        })
-    }
-    /// Remainder `a % b`
-    pub fn rem(lhs, rhs) -> IResult<ConValue> {
-        Ok(match (lhs, rhs) {
-            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a % b),
-            _ => Err(Error::TypeError)?,
-        })
-    }
-
-    /// Addition `a + b`
-    pub fn add(lhs, rhs) -> IResult<ConValue> {
-        Ok(match (lhs, rhs) {
-            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a + b),
-            (ConValue::String(a), ConValue::String(b)) => ConValue::String(a.to_string() + b),
-            _ => Err(Error::TypeError)?
-        })
-    }
-    /// Subtraction `a - b`
-    pub fn sub(lhs, rhs) -> IResult<ConValue> {
-        Ok(match (lhs, rhs) {
-            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a - b),
-            _ => Err(Error::TypeError)?,
-        })
-    }
-
-    /// Shift Left `a << b`
-    pub fn shl(lhs, rhs) -> IResult<ConValue> {
-        Ok(match (lhs, rhs) {
-            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a << b),
-            _ => Err(Error::TypeError)?,
-        })
-    }
-    /// Shift Right `a >> b`
-    pub fn shr(lhs, rhs) -> IResult<ConValue> {
-        Ok(match (lhs, rhs) {
-            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a >> b),
-            _ => Err(Error::TypeError)?,
-        })
-    }
-
-    /// Bitwise And `a & b`
-    pub fn and(lhs, rhs) -> IResult<ConValue> {
-        Ok(match (lhs, rhs) {
-            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a & b),
-            (ConValue::Bool(a), ConValue::Bool(b)) => ConValue::Bool(a & b),
-            _ => Err(Error::TypeError)?,
-        })
-    }
-    /// Bitwise Or `a | b`
-    pub fn or(lhs, rhs) -> IResult<ConValue> {
-        Ok(match (lhs, rhs) {
-            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a | b),
-            (ConValue::Bool(a), ConValue::Bool(b)) => ConValue::Bool(a | b),
-            _ => Err(Error::TypeError)?,
-        })
-    }
-    /// Bitwise Exclusive Or `a ^ b`
-    pub fn xor(lhs, rhs) -> IResult<ConValue> {
-        Ok(match (lhs, rhs) {
-            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a ^ b),
-            (ConValue::Bool(a), ConValue::Bool(b)) => ConValue::Bool(a ^ b),
-            _ => Err(Error::TypeError)?,
-        })
-    }
-
-    /// Tests whether `a < b`
-    pub fn lt(lhs, rhs) -> IResult<ConValue> {
-        cmp!(lhs, rhs, false, <)
-    }
-    /// Tests whether `a <= b`
-    pub fn lt_eq(lhs, rhs) -> IResult<ConValue> {
-        cmp!(lhs, rhs, true, <=)
-    }
-    /// Tests whether `a == b`
-    pub fn eq(lhs, rhs) -> IResult<ConValue> {
-        cmp!(lhs, rhs, true, ==)
-    }
-    /// Tests whether `a != b`
-    pub fn neq(lhs, rhs) -> IResult<ConValue> {
-        cmp!(lhs, rhs, false, !=)
-    }
-    /// Tests whether `a <= b`
-    pub fn gt_eq(lhs, rhs) -> IResult<ConValue> {
-        cmp!(lhs, rhs, true, >=)
-    }
-    /// Tests whether `a < b`
-    pub fn gt(lhs, rhs) -> IResult<ConValue> {
-        cmp!(lhs, rhs, false, >)
-    }
-}
-builtins! {
-    const RANGE;
-    /// Exclusive Range `a..b`
-    pub fn range_exc(lhs, rhs) -> IResult<ConValue> {
-        let (&ConValue::Int(lhs), &ConValue::Int(rhs)) = (lhs, rhs) else {
-            Err(Error::TypeError)?
-        };
-        Ok(ConValue::RangeExc(lhs, rhs.saturating_sub(1)))
-    }
-    /// Inclusive Range `a..=b`
-    pub fn range_inc(lhs, rhs) -> IResult<ConValue> {
-        let (&ConValue::Int(lhs), &ConValue::Int(rhs)) = (lhs, rhs) else {
-            Err(Error::TypeError)?
-        };
-        Ok(ConValue::RangeInc(lhs, rhs))
-    }
-}
-builtins! {
-    const UNARY;
-    /// Negates the ConValue
-    pub fn neg(tail) -> IResult<ConValue> {
-        Ok(match tail {
-            ConValue::Empty => ConValue::Empty,
-            ConValue::Int(v) => ConValue::Int(-v),
-            _ => Err(Error::TypeError)?,
-        })
-    }
-    /// Inverts the ConValue
-    pub fn not(tail) -> IResult<ConValue> {
-        Ok(match tail {
-            ConValue::Empty => ConValue::Empty,
-            ConValue::Int(v) => ConValue::Int(!v),
-            ConValue::Bool(v) => ConValue::Bool(!v),
-            _ => Err(Error::TypeError)?,
-        })
-    }
-}
-
-/// Turns an argument slice into an array with the (inferred) correct number of elements
-pub fn to_args<const N: usize>(args: &[ConValue]) -> IResult<&[ConValue; N]> {
-    args.try_into()
-        .map_err(|_| Error::ArgNumber { want: N, got: args.len() })
-}
-
-/// Turns function definitions into ZSTs which implement [Callable] and [BuiltIn]
-macro builtins (
-    $(prefix = $prefix:literal)?
-    const $defaults:ident $( = [$($additional_builtins:expr),*$(,)?])?;
-    $(
-        $(#[$meta:meta])*$vis:vis fn $name:ident$(<$env:tt, $args:tt>)? ( $($($arg:tt),+$(,)?)? ) $(-> $rety:ty)?
-            $body:block
-    )*
-) {
-    /// Builtins to load when a new interpreter is created
-    pub const $defaults: &[&dyn BuiltIn] = &[$(&$name,)* $($additional_builtins)*];
-    $(
-        $(#[$meta])* #[allow(non_camel_case_types)] #[derive(Clone, Debug)]
-        /// ```rust,ignore
-        #[doc = stringify!(builtin! fn $name($($($arg),*)?) $(-> $rety)? $body)]
-        /// ```
-        $vis struct $name;
-        impl BuiltIn for $name {
-            fn description(&self) -> &str { concat!("builtin ", stringify!($name), stringify!(($($($arg),*)?) )) }
-        }
-        impl Callable for $name {
-            #[allow(unused)]
-            fn call(&self, env: &mut Environment, args: &[ConValue]) $(-> $rety)? {
-                // println!("{}", stringify!($name), );
-                $(let $env = env;
-                let $args = args;)?
-                $(let [$($arg),*] = to_args(args)?;)?
-                $body
-            }
-            fn name(&self) -> &str { stringify!($name) }
-        }
-    )*
-}
-
-/// Templates comparison functions for [ConValue]
-macro cmp ($a:expr, $b:expr, $empty:literal, $op:tt) {
-    match ($a, $b) {
-        (ConValue::Empty, ConValue::Empty) => Ok(ConValue::Bool($empty)),
-        (ConValue::Int(a), ConValue::Int(b)) => Ok(ConValue::Bool(a $op b)),
-        (ConValue::Bool(a), ConValue::Bool(b)) => Ok(ConValue::Bool(a $op b)),
-        (ConValue::Char(a), ConValue::Char(b)) => Ok(ConValue::Bool(a $op b)),
-        (ConValue::String(a), ConValue::String(b)) => Ok(ConValue::Bool(a $op b)),
-        _ => Err(Error::TypeError)
-    }
-}

cl-interpret/src/interpret.rs

@@ -1,447 +0,0 @@
-//! A work-in-progress tree walk interpreter for Conlang
-//!
-//! Currently, major parts of the interpreter are not yet implemented, and major parts will never be
-//! implemented in its current form. Namely, since no [ConValue] has a stable location, it's
-//! meaningless to get a pointer to one, and would be undefined behavior to dereference a pointer to
-//! one in any situation.
-
-use std::borrow::Borrow;
-
-use super::*;
-use cl_ast::*;
-/// A work-in-progress tree walk interpreter for Conlang
-pub trait Interpret {
-    /// Interprets this thing in the given [`Environment`].
-    ///
-    /// Everything returns a value!™
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue>;
-}
-
-impl Interpret for File {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        for item in &self.items {
-            item.interpret(env)?;
-        }
-        Ok(ConValue::Empty)
-    }
-}
-impl Interpret for Item {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        match &self.kind {
-            ItemKind::Alias(item) => item.interpret(env),
-            ItemKind::Const(item) => item.interpret(env),
-            ItemKind::Static(item) => item.interpret(env),
-            ItemKind::Module(item) => item.interpret(env),
-            ItemKind::Function(item) => item.interpret(env),
-            ItemKind::Struct(item) => item.interpret(env),
-            ItemKind::Enum(item) => item.interpret(env),
-            ItemKind::Impl(item) => item.interpret(env),
-        }
-    }
-}
-impl Interpret for Alias {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        todo!("Interpret type alias in {env}")
-    }
-}
-impl Interpret for Const {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        todo!("interpret const in {env}")
-    }
-}
-impl Interpret for Static {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        todo!("interpret static in {env}")
-    }
-}
-impl Interpret for Module {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        // TODO: Enter this module's namespace
-        match &self.kind {
-            ModuleKind::Inline(file) => file.interpret(env),
-            ModuleKind::Outline => todo!("Load and parse external files"),
-        }
-    }
-}
-impl Interpret for Function {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        // register the function in the current environment
-        env.insert_fn(self);
-        Ok(ConValue::Empty)
-    }
-}
-impl Interpret for Struct {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        todo!("Interpret structs in {env}")
-    }
-}
-impl Interpret for Enum {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        todo!("Interpret enums in {env}")
-    }
-}
-impl Interpret for Impl {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        todo!("Enter a struct's namespace and insert function definitions into it in {env}");
-    }
-}
-impl Interpret for Stmt {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        let Self { extents: _, kind, semi } = self;
-        let out = match kind {
-            StmtKind::Empty => ConValue::Empty,
-            StmtKind::Local(stmt) => stmt.interpret(env)?,
-            StmtKind::Item(stmt) => stmt.interpret(env)?,
-            StmtKind::Expr(stmt) => stmt.interpret(env)?,
-        };
-        Ok(match semi {
-            Semi::Terminated => ConValue::Empty,
-            Semi::Unterminated => out,
-        })
-    }
-}
-impl Interpret for Let {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        let Let { mutable: _, name: Identifier(name), ty: _, init } = self;
-        let init = init.as_ref().map(|i| i.interpret(env)).transpose()?;
-        env.insert(name, init);
-        Ok(ConValue::Empty)
-    }
-}
-impl Interpret for Expr {
-    #[inline]
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        let Self { extents: _, kind } = self;
-        kind.interpret(env)
-    }
-}
-impl Interpret for ExprKind {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        match self {
-            ExprKind::Assign(v) => v.interpret(env),
-            ExprKind::Binary(v) => v.interpret(env),
-            ExprKind::Unary(v) => v.interpret(env),
-            ExprKind::Index(v) => v.interpret(env),
-            ExprKind::Path(v) => v.interpret(env),
-            ExprKind::Literal(v) => v.interpret(env),
-            ExprKind::Array(v) => v.interpret(env),
-            ExprKind::ArrayRep(v) => v.interpret(env),
-            ExprKind::AddrOf(v) => v.interpret(env),
-            ExprKind::Block(v) => v.interpret(env),
-            ExprKind::Empty => Ok(ConValue::Empty),
-            ExprKind::Group(v) => v.interpret(env),
-            ExprKind::Tuple(v) => v.interpret(env),
-            ExprKind::While(v) => v.interpret(env),
-            ExprKind::If(v) => v.interpret(env),
-            ExprKind::For(v) => v.interpret(env),
-            ExprKind::Break(v) => v.interpret(env),
-            ExprKind::Return(v) => v.interpret(env),
-            ExprKind::Continue(v) => v.interpret(env),
-        }
-    }
-}
-impl Interpret for Assign {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        let Assign { kind: op, parts } = self;
-        let (head, tail) = parts.borrow();
-        // Resolve the head pattern
-        let head = match &head {
-            ExprKind::Path(Path { parts, .. }) if parts.len() == 1 => {
-                match parts.last().expect("parts should not be empty") {
-                    PathPart::SuperKw => Err(Error::NotAssignable)?,
-                    PathPart::SelfKw => todo!("Assignment to `self`"),
-                    PathPart::Ident(Identifier(s)) => s,
-                }
-            }
-            ExprKind::Index(_) => todo!("Assignment to an index operation"),
-            ExprKind::Path(_) => todo!("Path expression resolution (IMPORTANT)"),
-            ExprKind::Empty | ExprKind::Group(_) | ExprKind::Tuple(_) => {
-                todo!("Pattern Destructuring?")
-            }
-            _ => Err(Error::NotAssignable)?,
-        };
-        // Get the initializer and the tail
-        let init = tail.interpret(env)?;
-        let target = env.get_mut(head)?;
-
-        if let AssignKind::Plain = op {
-            use std::mem::discriminant as variant;
-            // runtime typecheck
-            match target {
-                Some(value) if variant(value) == variant(&init) => {
-                    *value = init;
-                }
-                value @ None => *value = Some(init),
-                _ => Err(Error::TypeError)?,
-            }
-            return Ok(ConValue::Empty);
-        }
-        let Some(target) = target else {
-            return Err(Error::NotInitialized(head.into()));
-        };
-
-        match op {
-            AssignKind::Add => target.add_assign(init)?,
-            AssignKind::Sub => target.sub_assign(init)?,
-            AssignKind::Mul => target.mul_assign(init)?,
-            AssignKind::Div => target.div_assign(init)?,
-            AssignKind::Rem => target.rem_assign(init)?,
-            AssignKind::And => target.bitand_assign(init)?,
-            AssignKind::Or => target.bitor_assign(init)?,
-            AssignKind::Xor => target.bitxor_assign(init)?,
-            AssignKind::Shl => target.shl_assign(init)?,
-            AssignKind::Shr => target.shr_assign(init)?,
-            _ => (),
-        }
-        Ok(ConValue::Empty)
-    }
-}
-impl Interpret for Binary {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        let Binary { kind, parts } = self;
-        let (head, tail) = parts.borrow();
-
-        let head = head.interpret(env)?;
-
-        // Short-circuiting ops
-        match kind {
-            BinaryKind::LogAnd => {
-                return if head.truthy()? {
-                    tail.interpret(env)
-                } else {
-                    Ok(head)
-                }; // Short circuiting
-            }
-            BinaryKind::LogOr => {
-                return if !head.truthy()? {
-                    tail.interpret(env)
-                } else {
-                    Ok(head)
-                }; // Short circuiting
-            }
-            BinaryKind::LogXor => {
-                return Ok(ConValue::Bool(
-                    head.truthy()? ^ tail.interpret(env)?.truthy()?,
-                ));
-            }
-            _ => {}
-        }
-        let tail = tail.interpret(env)?;
-        match kind {
-            BinaryKind::Mul => env.call("mul", &[head, tail]),
-            BinaryKind::Div => env.call("div", &[head, tail]),
-            BinaryKind::Rem => env.call("rem", &[head, tail]),
-            BinaryKind::Add => env.call("add", &[head, tail]),
-            BinaryKind::Sub => env.call("sub", &[head, tail]),
-            BinaryKind::Shl => env.call("shl", &[head, tail]),
-            BinaryKind::Shr => env.call("shr", &[head, tail]),
-            BinaryKind::BitAnd => env.call("and", &[head, tail]),
-            BinaryKind::BitOr => env.call("or", &[head, tail]),
-            BinaryKind::BitXor => env.call("xor", &[head, tail]),
-            BinaryKind::RangeExc => env.call("range_exc", &[head, tail]),
-            BinaryKind::RangeInc => env.call("range_inc", &[head, tail]),
-            BinaryKind::Lt => env.call("lt", &[head, tail]),
-            BinaryKind::LtEq => env.call("lt_eq", &[head, tail]),
-            BinaryKind::Equal => env.call("eq", &[head, tail]),
-            BinaryKind::NotEq => env.call("neq", &[head, tail]),
-            BinaryKind::GtEq => env.call("gt_eq", &[head, tail]),
-            BinaryKind::Gt => env.call("gt", &[head, tail]),
-            BinaryKind::Dot => todo!("search within a type's namespace!"),
-            BinaryKind::Call => match tail {
-                ConValue::Empty => head.call(env, &[]),
-                ConValue::Tuple(args) => head.call(env, &args),
-                _ => Err(Error::TypeError),
-            },
-            _ => Ok(head),
-        }
-    }
-}
-
-impl Interpret for Unary {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        let Unary { kind, tail } = self;
-        let operand = tail.interpret(env)?;
-        match kind {
-            UnaryKind::Deref => env.call("deref", &[operand]),
-            UnaryKind::Neg => env.call("neg", &[operand]),
-            UnaryKind::Not => env.call("not", &[operand]),
-            UnaryKind::At => {
-                println!("{operand}");
-                Ok(operand)
-            }
-            UnaryKind::Tilde => unimplemented!("Tilde operator"),
-        }
-    }
-}
-impl Interpret for Index {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        let Self { head, indices } = self;
-        let mut head = head.interpret(env)?;
-        for index in indices {
-            head = head.index(&index.interpret(env)?)?;
-        }
-        Ok(head)
-    }
-}
-impl Interpret for Path {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        let Self { absolute: _, parts } = self;
-
-        if parts.len() == 1 {
-            match parts.last().expect("parts should not be empty") {
-                PathPart::SuperKw | PathPart::SelfKw => todo!("Path navigation"),
-                PathPart::Ident(Identifier(s)) => env.get(s).cloned(),
-            }
-        } else {
-            todo!("Path navigation!")
-        }
-    }
-}
-impl Interpret for Literal {
-    fn interpret(&self, _env: &mut Environment) -> IResult<ConValue> {
-        Ok(match self {
-            Literal::String(value) => ConValue::from(value.as_str()),
-            Literal::Char(value) => ConValue::Char(*value),
-            Literal::Bool(value) => ConValue::Bool(*value),
-            // Literal::Float(value) => todo!("Float values in interpreter: {value:?}"),
-            Literal::Int(value) => ConValue::Int(*value as _),
-        })
-    }
-}
-impl Interpret for Array {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        let Self { values } = self;
-        let mut out = vec![];
-        for expr in values {
-            out.push(expr.interpret(env)?)
-        }
-        Ok(ConValue::Array(out))
-    }
-}
-impl Interpret for ArrayRep {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        let Self { value, repeat } = self;
-        let repeat = match repeat.interpret(env)? {
-            ConValue::Int(v) => v,
-            _ => Err(Error::TypeError)?,
-        };
-        let value = value.interpret(env)?;
-        Ok(ConValue::Array(vec![value; repeat as usize]))
-    }
-}
-impl Interpret for AddrOf {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        let Self { count: _, mutable: _, expr } = self;
-        // this is stupid
-        todo!("Create reference\nfrom expr: {expr}\nin env:\n{env}\n")
-    }
-}
-impl Interpret for Block {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        let Self { stmts } = self;
-        let mut env = env.frame("block");
-        let mut out = ConValue::Empty;
-        for stmt in stmts {
-            out = stmt.interpret(&mut env)?;
-        }
-        Ok(out)
-    }
-}
-impl Interpret for Group {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        let Self { expr } = self;
-        expr.interpret(env)
-    }
-}
-impl Interpret for Tuple {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        let Self { exprs } = self;
-        Ok(ConValue::Tuple(exprs.iter().try_fold(
-            vec![],
-            |mut out, element| {
-                out.push(element.interpret(env)?);
-                Ok(out)
-            },
-        )?))
-    }
-}
-impl Interpret for While {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        let Self { cond, pass, fail } = self;
-        while cond.interpret(env)?.truthy()? {
-            match pass.interpret(env) {
-                Err(Error::Break(value)) => return Ok(value),
-                Err(Error::Continue) => continue,
-                e => e?,
-            };
-        }
-        fail.interpret(env)
-    }
-}
-impl Interpret for If {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        let Self { cond, pass, fail } = self;
-        if cond.interpret(env)?.truthy()? {
-            pass.interpret(env)
-        } else {
-            fail.interpret(env)
-        }
-    }
-}
-impl Interpret for For {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        let Self { bind: Identifier(name), cond, pass, fail } = self;
-        // TODO: A better iterator model
-        let bounds = match cond.interpret(env)? {
-            ConValue::RangeExc(a, b) => a..=b,
-            ConValue::RangeInc(a, b) => a..=b,
-            _ => Err(Error::TypeError)?,
-        };
-        {
-            let mut env = env.frame("loop variable");
-            for loop_var in bounds {
-                env.insert(name, Some(loop_var.into()));
-                match pass.interpret(&mut env) {
-                    Err(Error::Break(value)) => return Ok(value),
-                    Err(Error::Continue) => continue,
-                    result => result?,
-                };
-            }
-        }
-        fail.interpret(env)
-    }
-}
-impl Interpret for Else {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        let Self { body } = self;
-        match body {
-            Some(body) => body.interpret(env),
-            None => Ok(ConValue::Empty),
-        }
-    }
-}
-impl Interpret for Continue {
-    fn interpret(&self, _env: &mut Environment) -> IResult<ConValue> {
-        Err(Error::Continue)
-    }
-}
-impl Interpret for Return {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        let Self { body } = self;
-        Err(Error::Return(
-            body.as_ref()
-                .map(|body| body.interpret(env))
-                .unwrap_or(Ok(ConValue::Empty))?,
-        ))
-    }
-}
-impl Interpret for Break {
-    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
-        let Self { body } = self;
-        Err(Error::Break(
-            body.as_ref()
-                .map(|body| body.interpret(env))
-                .unwrap_or(Ok(ConValue::Empty))?,
-        ))
-    }
-}

cl-interpret/src/lib.rs

@@ -1,614 +0,0 @@
-//! Walks a Conlang AST, interpreting it as a program.
-#![warn(clippy::all)]
-#![feature(decl_macro)]
-
-use env::Environment;
-use error::{Error, IResult};
-use interpret::Interpret;
-use temp_type_impl::ConValue;
-
-/// Callable types can be called from within a Conlang program
-pub trait Callable: std::fmt::Debug {
-    /// Calls this [Callable] in the provided [Environment], with [ConValue] args  \
-    /// The Callable is responsible for checking the argument count and validating types
-    fn call(&self, interpreter: &mut Environment, args: &[ConValue]) -> IResult<ConValue>;
-    /// Returns the common name of this identifier.
-    fn name(&self) -> &str;
-}
-
-/// [BuiltIn]s are [Callable]s with bespoke definitions
-pub trait BuiltIn: std::fmt::Debug + Callable {
-    fn description(&self) -> &str;
-}
-
-pub mod temp_type_impl {
-    //! Temporary implementations of Conlang values
-    //!
-    //! The most permanent fix is a temporary one.
-    use super::{
-        error::{Error, IResult},
-        function::Function,
-        BuiltIn, Callable, Environment,
-    };
-    use std::ops::*;
-
-    type Integer = isize;
-
-    /// A Conlang value
-    ///
-    /// This is a hack to work around the fact that Conlang doesn't
-    /// have a functioning type system yet :(
-    #[derive(Clone, Debug, Default)]
-    pub enum ConValue {
-        /// The empty/unit `()` type
-        #[default]
-        Empty,
-        /// An integer
-        Int(Integer),
-        /// A boolean
-        Bool(bool),
-        /// A unicode character
-        Char(char),
-        /// A string
-        String(String),
-        /// An Array
-        Array(Vec<ConValue>),
-        /// A tuple
-        Tuple(Vec<ConValue>),
-        /// An exclusive range
-        RangeExc(Integer, Integer),
-        /// An inclusive range
-        RangeInc(Integer, Integer),
-        /// A callable thing
-        Function(Function),
-        /// A built-in function
-        BuiltIn(&'static dyn BuiltIn),
-    }
-    impl ConValue {
-        /// Gets whether the current value is true or false
-        pub fn truthy(&self) -> IResult<bool> {
-            match self {
-                ConValue::Bool(v) => Ok(*v),
-                _ => Err(Error::TypeError)?,
-            }
-        }
-        pub fn range_exc(self, other: Self) -> IResult<Self> {
-            let (Self::Int(a), Self::Int(b)) = (self, other) else {
-                Err(Error::TypeError)?
-            };
-            Ok(Self::RangeExc(a, b.saturating_sub(1)))
-        }
-        pub fn range_inc(self, other: Self) -> IResult<Self> {
-            let (Self::Int(a), Self::Int(b)) = (self, other) else {
-                Err(Error::TypeError)?
-            };
-            Ok(Self::RangeInc(a, b))
-        }
-        pub fn index(&self, index: &Self) -> IResult<ConValue> {
-            let Self::Int(index) = index else {
-                Err(Error::TypeError)?
-            };
-            let Self::Array(arr) = self else {
-                Err(Error::TypeError)?
-            };
-            arr.get(*index as usize)
-                .cloned()
-                .ok_or(Error::OobIndex(*index as usize, arr.len()))
-        }
-        cmp! {
-            lt: false, <;
-            lt_eq: true, <=;
-            eq: true, ==;
-            neq: false, !=;
-            gt_eq: true, >=;
-            gt: false, >;
-        }
-        assign! {
-            add_assign: +;
-            bitand_assign: &;
-            bitor_assign: |;
-            bitxor_assign: ^;
-            div_assign: /;
-            mul_assign: *;
-            rem_assign: %;
-            shl_assign: <<;
-            shr_assign: >>;
-            sub_assign: -;
-        }
-    }
-
-    impl Callable for ConValue {
-        fn name(&self) -> &str {
-            match self {
-                ConValue::Function(func) => func.name(),
-                ConValue::BuiltIn(func) => func.name(),
-                _ => "",
-            }
-        }
-        fn call(&self, interpreter: &mut Environment, args: &[ConValue]) -> IResult<ConValue> {
-            match self {
-                Self::Function(func) => func.call(interpreter, args),
-                Self::BuiltIn(func) => func.call(interpreter, args),
-                _ => Err(Error::NotCallable(self.clone())),
-            }
-        }
-    }
-    /// Templates comparison functions for [ConValue]
-    macro cmp ($($fn:ident: $empty:literal, $op:tt);*$(;)?) {$(
-        /// TODO: Remove when functions are implemented:
-        ///       Desugar into function calls
-        pub fn $fn(&self, other: &Self) -> IResult<Self> {
-            match (self, other) {
-                (Self::Empty, Self::Empty) => Ok(Self::Bool($empty)),
-                (Self::Int(a), Self::Int(b)) => Ok(Self::Bool(a $op b)),
-                (Self::Bool(a), Self::Bool(b)) => Ok(Self::Bool(a $op b)),
-                (Self::Char(a), Self::Char(b)) => Ok(Self::Bool(a $op b)),
-                (Self::String(a), Self::String(b)) => Ok(Self::Bool(a $op b)),
-                _ => Err(Error::TypeError)
-            }
-        }
-    )*}
-    macro assign($( $fn: ident: $op: tt );*$(;)?) {$(
-        pub fn $fn(&mut self, other: Self) -> IResult<()> {
-            *self = (std::mem::take(self) $op other)?;
-            Ok(())
-        }
-    )*}
-    /// Implements [From] for an enum with 1-tuple variants
-    macro from ($($T:ty => $v:expr),*$(,)?) {
-        $(impl From<$T> for ConValue {
-            fn from(value: $T) -> Self { $v(value.into()) }
-        })*
-    }
-    from! {
-        Integer => ConValue::Int,
-        bool => ConValue::Bool,
-        char => ConValue::Char,
-        &str => ConValue::String,
-        String => ConValue::String,
-        Function => ConValue::Function,
-        Vec<ConValue> => ConValue::Tuple,
-        &'static dyn BuiltIn => ConValue::BuiltIn,
-    }
-    impl From<()> for ConValue {
-        fn from(_: ()) -> Self {
-            Self::Empty
-        }
-    }
-    impl From<&[ConValue]> for ConValue {
-        fn from(value: &[ConValue]) -> Self {
-            match value.len() {
-                0 => Self::Empty,
-                1 => value[0].clone(),
-                _ => Self::Tuple(value.into()),
-            }
-        }
-    }
-
-    /// Implements binary [std::ops] traits for [ConValue]
-    ///
-    /// TODO: Desugar operators into function calls
-    macro ops($($trait:ty: $fn:ident = [$($match:tt)*])*) {
-        $(impl $trait for ConValue {
-            type Output = IResult<Self>;
-            /// TODO: Desugar operators into function calls
-            fn $fn(self, rhs: Self) -> Self::Output {Ok(match (self, rhs) {$($match)*})}
-        })*
-    }
-    ops! {
-        Add: add = [
-            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a + b),
-            (ConValue::String(a), ConValue::String(b)) => ConValue::String(a + &b),
-            _ => Err(Error::TypeError)?
-            ]
-        BitAnd: bitand = [
-            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a & b),
-            (ConValue::Bool(a), ConValue::Bool(b)) => ConValue::Bool(a & b),
-            _ => Err(Error::TypeError)?
-        ]
-        BitOr: bitor = [
-            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a | b),
-            (ConValue::Bool(a), ConValue::Bool(b)) => ConValue::Bool(a | b),
-            _ => Err(Error::TypeError)?
-        ]
-        BitXor: bitxor = [
-            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a ^ b),
-            (ConValue::Bool(a), ConValue::Bool(b)) => ConValue::Bool(a ^ b),
-            _ => Err(Error::TypeError)?
-        ]
-        Div: div = [
-            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a / b),
-            _ => Err(Error::TypeError)?
-        ]
-        Mul: mul = [
-            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a * b),
-            _ => Err(Error::TypeError)?
-        ]
-        Rem: rem = [
-            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a % b),
-            _ => Err(Error::TypeError)?
-        ]
-        Shl: shl = [
-            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a << b),
-            _ => Err(Error::TypeError)?
-        ]
-        Shr: shr = [
-            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a >> b),
-            _ => Err(Error::TypeError)?
-        ]
-        Sub: sub = [
-            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a - b),
-            _ => Err(Error::TypeError)?
-        ]
-    }
-    impl std::fmt::Display for ConValue {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            match self {
-                ConValue::Empty => "Empty".fmt(f),
-                ConValue::Int(v) => v.fmt(f),
-                ConValue::Bool(v) => v.fmt(f),
-                ConValue::Char(v) => v.fmt(f),
-                ConValue::String(v) => v.fmt(f),
-                ConValue::Array(array) => {
-                    '['.fmt(f)?;
-                    for (idx, element) in array.iter().enumerate() {
-                        if idx > 0 {
-                            ", ".fmt(f)?
-                        }
-                        element.fmt(f)?
-                    }
-                    ']'.fmt(f)
-                }
-                ConValue::RangeExc(a, b) => write!(f, "{a}..{}", b + 1),
-                ConValue::RangeInc(a, b) => write!(f, "{a}..={b}"),
-                ConValue::Tuple(tuple) => {
-                    '('.fmt(f)?;
-                    for (idx, element) in tuple.iter().enumerate() {
-                        if idx > 0 {
-                            ", ".fmt(f)?
-                        }
-                        element.fmt(f)?
-                    }
-                    ')'.fmt(f)
-                }
-                ConValue::Function(func) => {
-                    use cl_ast::format::*;
-                    use std::fmt::Write;
-                    write!(f.pretty(), "{}", func.decl())
-                }
-                ConValue::BuiltIn(func) => {
-                    write!(f, "{}", func.description())
-                }
-            }
-        }
-    }
-}
-
-pub mod interpret;
-
-pub mod function {
-    //! Represents a block of code which lives inside the Interpreter
-    use super::{Callable, ConValue, Environment, Error, IResult, Interpret};
-    use cl_ast::{Function as FnDecl, Identifier, Param};
-    /// Represents a block of code which persists inside the Interpreter
-    #[derive(Clone, Debug)]
-    pub struct Function {
-        /// Stores the contents of the function declaration
-        decl: Box<FnDecl>,
-        // /// Stores the enclosing scope of the function
-        // env: Box<Environment>,
-    }
-
-    impl Function {
-        pub fn new(decl: &FnDecl) -> Self {
-            Self { decl: decl.clone().into() }
-        }
-        pub fn decl(&self) -> &FnDecl {
-            &self.decl
-        }
-    }
-
-    impl Callable for Function {
-        fn name(&self) -> &str {
-            let FnDecl { name: Identifier(ref name), .. } = *self.decl;
-            name
-        }
-        fn call(&self, env: &mut Environment, args: &[ConValue]) -> IResult<ConValue> {
-            let FnDecl { name: Identifier(name), args: declargs, body, rety: _ } = &*self.decl;
-            // Check arg mapping
-            if args.len() != declargs.len() {
-                return Err(Error::ArgNumber { want: declargs.len(), got: args.len() });
-            }
-            let Some(body) = body else {
-                return Err(Error::NotDefined(name.into()));
-            };
-            // TODO: completely refactor data storage
-            let mut frame = env.frame("fn args");
-            for (Param { mutability: _, name: Identifier(name), ty: _ }, value) in
-                declargs.iter().zip(args)
-            {
-                frame.insert(name, Some(value.clone()));
-            }
-            match body.interpret(&mut frame) {
-                Err(Error::Return(value)) => Ok(value),
-                Err(Error::Break(value)) => Err(Error::BadBreak(value)),
-                result => result,
-            }
-        }
-    }
-}
-
-pub mod builtin;
-
-pub mod env {
-    //! Lexical and non-lexical scoping for variables
-    use super::{
-        builtin::{BINARY, MISC, RANGE, UNARY},
-        error::{Error, IResult},
-        function::Function,
-        temp_type_impl::ConValue,
-        BuiltIn, Callable, Interpret,
-    };
-    use cl_ast::{Function as FnDecl, Identifier};
-    use std::{
-        collections::HashMap,
-        fmt::Display,
-        ops::{Deref, DerefMut},
-    };
-
-    /// Implements a nested lexical scope
-    #[derive(Clone, Debug)]
-    pub struct Environment {
-        frames: Vec<(HashMap<String, Option<ConValue>>, &'static str)>,
-    }
-
-    impl Display for Environment {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            for (frame, name) in self.frames.iter().rev() {
-                writeln!(f, "--- {name} ---")?;
-                for (var, val) in frame {
-                    write!(f, "{var}: ")?;
-                    match val {
-                        Some(value) => writeln!(f, "\t{value}"),
-                        None => writeln!(f, "<undefined>"),
-                    }?
-                }
-            }
-            Ok(())
-        }
-    }
-    impl Default for Environment {
-        fn default() -> Self {
-            Self {
-                frames: vec![
-                    (to_hashmap(RANGE), "range ops"),
-                    (to_hashmap(UNARY), "unary ops"),
-                    (to_hashmap(BINARY), "binary ops"),
-                    (to_hashmap(MISC), "builtins"),
-                    (HashMap::new(), "globals"),
-                ],
-            }
-        }
-    }
-    fn to_hashmap(from: &[&'static dyn BuiltIn]) -> HashMap<String, Option<ConValue>> {
-        from.iter()
-            .map(|&v| (v.name().into(), Some(v.into())))
-            .collect()
-    }
-
-    impl Environment {
-        pub fn new() -> Self {
-            Self::default()
-        }
-        /// Creates an [Environment] with no [builtins](super::builtin)
-        pub fn no_builtins(name: &'static str) -> Self {
-            Self { frames: vec![(Default::default(), name)] }
-        }
-
-        pub fn eval(&mut self, node: &impl Interpret) -> IResult<ConValue> {
-            node.interpret(self)
-        }
-
-        /// Calls a function inside the interpreter's scope,
-        /// and returns the result
-        pub fn call(&mut self, name: &str, args: &[ConValue]) -> IResult<ConValue> {
-            // FIXME: Clone to satisfy the borrow checker
-            let function = self.get(name)?.clone();
-            function.call(self, args)
-        }
-        /// Enters a nested scope, returning a [`Frame`] stack-guard.
-        ///
-        /// [`Frame`] implements Deref/DerefMut for [`Environment`].
-        pub fn frame(&mut self, name: &'static str) -> Frame {
-            Frame::new(self, name)
-        }
-        /// Resolves a variable mutably.
-        ///
-        /// Returns a mutable reference to the variable's record, if it exists.
-        pub fn get_mut(&mut self, id: &str) -> IResult<&mut Option<ConValue>> {
-            for (frame, _) in self.frames.iter_mut().rev() {
-                if let Some(var) = frame.get_mut(id) {
-                    return Ok(var);
-                }
-            }
-            Err(Error::NotDefined(id.into()))
-        }
-        /// Resolves a variable immutably.
-        ///
-        /// Returns a reference to the variable's contents, if it is defined and initialized.
-        pub fn get(&self, id: &str) -> IResult<&ConValue> {
-            for (frame, _) in self.frames.iter().rev() {
-                match frame.get(id) {
-                    Some(Some(var)) => return Ok(var),
-                    Some(None) => return Err(Error::NotInitialized(id.into())),
-                    _ => (),
-                }
-            }
-            Err(Error::NotDefined(id.into()))
-        }
-        /// Inserts a new [ConValue] into this [Environment]
-        pub fn insert(&mut self, id: &str, value: Option<ConValue>) {
-            if let Some((frame, _)) = self.frames.last_mut() {
-                frame.insert(id.into(), value);
-            }
-        }
-        /// A convenience function for registering a [FnDecl] as a [Function]
-        pub fn insert_fn(&mut self, decl: &FnDecl) {
-            let FnDecl { name: Identifier(name), .. } = decl;
-            let (name, function) = (name.clone(), Some(Function::new(decl).into()));
-            if let Some((frame, _)) = self.frames.last_mut() {
-                frame.insert(name, function);
-            }
-        }
-    }
-
-    /// Functions which aid in the implementation of [`Frame`]
-    impl Environment {
-        /// Enters a scope, creating a new namespace for variables
-        fn enter(&mut self, name: &'static str) -> &mut Self {
-            self.frames.push((Default::default(), name));
-            self
-        }
-
-        /// Exits the scope, destroying all local variables and
-        /// returning the outer scope, if there is one
-        fn exit(&mut self) -> &mut Self {
-            if self.frames.len() > 2 {
-                self.frames.pop();
-            }
-            self
-        }
-    }
-
-    /// Represents a stack frame
-    #[derive(Debug)]
-    pub struct Frame<'scope> {
-        scope: &'scope mut Environment,
-    }
-    impl<'scope> Frame<'scope> {
-        fn new(scope: &'scope mut Environment, name: &'static str) -> Self {
-            Self { scope: scope.enter(name) }
-        }
-    }
-    impl<'scope> Deref for Frame<'scope> {
-        type Target = Environment;
-        fn deref(&self) -> &Self::Target {
-            self.scope
-        }
-    }
-    impl<'scope> DerefMut for Frame<'scope> {
-        fn deref_mut(&mut self) -> &mut Self::Target {
-            self.scope
-        }
-    }
-    impl<'scope> Drop for Frame<'scope> {
-        fn drop(&mut self) {
-            self.scope.exit();
-        }
-    }
-}
-
-pub mod error {
-    //! The [Error] type represents any error thrown by the [Environment](super::Environment)
-
-    use super::temp_type_impl::ConValue;
-
-    pub type IResult<T> = Result<T, Error>;
-
-    /// Represents any error thrown by the [Environment](super::Environment)
-    #[derive(Clone, Debug)]
-    pub enum Error {
-        /// Propagate a Return value
-        Return(ConValue),
-        /// Propagate a Break value
-        Break(ConValue),
-        /// Break propagated across function bounds
-        BadBreak(ConValue),
-        /// Continue to the next iteration of a loop
-        Continue,
-        /// Underflowed the stack
-        StackUnderflow,
-        /// Exited the last scope
-        ScopeExit,
-        /// Type incompatibility
-        // TODO: store the type information in this error
-        TypeError,
-        /// In clause of For loop didn't yield a Range
-        NotIterable,
-        /// A value could not be indexed
-        NotIndexable,
-        /// An array index went out of bounds
-        OobIndex(usize, usize),
-        /// An expression is not assignable
-        NotAssignable,
-        /// A name was not defined in scope before being used
-        NotDefined(String),
-        /// A name was defined but not initialized
-        NotInitialized(String),
-        /// A value was called, but is not callable
-        NotCallable(ConValue),
-        /// A function was called with the wrong number of arguments
-        ArgNumber {
-            want: usize,
-            got: usize,
-        },
-        NullPointer,
-    }
-
-    impl std::error::Error for Error {}
-    impl std::fmt::Display for Error {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            match self {
-                Error::Return(value) => write!(f, "return {value}"),
-                Error::Break(value) => write!(f, "break {value}"),
-                Error::BadBreak(value) => write!(f, "rogue break: {value}"),
-                Error::Continue => "continue".fmt(f),
-                Error::StackUnderflow => "Stack underflow".fmt(f),
-                Error::ScopeExit => "Exited the last scope. This is a logic bug.".fmt(f),
-                Error::TypeError => "Incompatible types".fmt(f),
-                Error::NotIterable => "`in` clause of `for` loop did not yield an iterable".fmt(f),
-                Error::NotIndexable => {
-                    write!(f, "expression cannot be indexed")
-                }
-                Error::OobIndex(idx, len) => {
-                    write!(f, "Index out of bounds: index was {idx}. but len is {len}")
-                }
-                Error::NotAssignable => {
-                    write!(f, "expression is not assignable")
-                }
-                Error::NotDefined(value) => {
-                    write!(f, "{value} not bound. Did you mean `let {value};`?")
-                }
-                Error::NotInitialized(value) => {
-                    write!(f, "{value} bound, but not initialized")
-                }
-                Error::NotCallable(value) => {
-                    write!(f, "{value} is not callable.")
-                }
-                Error::ArgNumber { want, got } => {
-                    write!(
-                        f,
-                        "Expected {want} argument{}, got {got}",
-                        if *want == 1 { "" } else { "s" }
-                    )
-                }
-                Error::NullPointer => {
-                    write!(f, "Attempted to dereference a null pointer?")
-                }
-            }
-        }
-    }
-}
-
-#[cfg(test)]
-mod tests;

cl-lexer/src/lib.rs

@@ -1,556 +0,0 @@
-//! Converts a text file into tokens
-#![warn(clippy::all)]
-#![feature(decl_macro)]
-use cl_structures::span::Loc;
-use cl_token::{TokenKind as Kind, *};
-use std::{
-    iter::Peekable,
-    str::{Chars, FromStr},
-};
-use unicode_ident::*;
-
-#[cfg(test)]
-mod tests;
-
-pub mod lexer_iter {
-    //! Iterator over a [`Lexer`], returning [`LResult<Token>`]s
-    use super::{
-        error::{LResult, Reason},
-        Lexer, Token,
-    };
-
-    /// Iterator over a [`Lexer`], returning [`LResult<Token>`]s
-    pub struct LexerIter<'t> {
-        lexer: Lexer<'t>,
-    }
-    impl<'t> Iterator for LexerIter<'t> {
-        type Item = LResult<Token>;
-        fn next(&mut self) -> Option<Self::Item> {
-            match self.lexer.scan() {
-                Ok(v) => Some(Ok(v)),
-                Err(e) => {
-                    if e.reason == Reason::EndOfFile {
-                        None
-                    } else {
-                        Some(Err(e))
-                    }
-                }
-            }
-        }
-    }
-    impl<'t> IntoIterator for Lexer<'t> {
-        type Item = LResult<Token>;
-        type IntoIter = LexerIter<'t>;
-        fn into_iter(self) -> Self::IntoIter {
-            LexerIter { lexer: self }
-        }
-    }
-}
-
-/// The Lexer iterates over the characters in a body of text, searching for [Tokens](Token).
-///
-/// # Examples
-/// ```rust
-/// # use cl_lexer::Lexer;
-/// # fn main() -> Result<(), Box<dyn std::error::Error>> {
-/// // Read in your code from somewhere
-/// let some_code = "
-/// fn main () {
-///     // TODO: code goes here!
-/// }
-/// ";
-/// // Create a lexer over your code
-/// let mut lexer = Lexer::new(some_code);
-/// // Scan for a single token
-/// let first_token = lexer.scan()?;
-/// println!("{first_token:?}");
-/// // Loop over all the rest of the tokens
-/// for token in lexer {
-/// #   let token: Result<_,()> = Ok(token?);
-///     match token {
-///         Ok(token) => println!("{token:?}"),
-///         Err(e) => eprintln!("{e:?}"),
-///     }
-/// }
-/// # Ok(()) }
-/// ```
-#[derive(Clone, Debug)]
-pub struct Lexer<'t> {
-    iter: Peekable<Chars<'t>>,
-    start: usize,
-    start_loc: (u32, u32),
-    current: usize,
-    current_loc: (u32, u32),
-}
-
-impl<'t> Lexer<'t> {
-    /// Creates a new [Lexer] over a [str]
-    pub fn new(text: &'t str) -> Self {
-        Self {
-            iter: text.chars().peekable(),
-            start: 0,
-            start_loc: (1, 1),
-            current: 0,
-            current_loc: (1, 1),
-        }
-    }
-    /// Scans through the text, searching for the next [Token]
-    pub fn scan(&mut self) -> LResult<Token> {
-        match self.skip_whitespace().peek()? {
-            '{' => self.consume()?.produce_op(Punct::LCurly),
-            '}' => self.consume()?.produce_op(Punct::RCurly),
-            '[' => self.consume()?.produce_op(Punct::LBrack),
-            ']' => self.consume()?.produce_op(Punct::RBrack),
-            '(' => self.consume()?.produce_op(Punct::LParen),
-            ')' => self.consume()?.produce_op(Punct::RParen),
-            '&' => self.consume()?.amp(),
-            '@' => self.consume()?.produce_op(Punct::At),
-            '\\' => self.consume()?.produce_op(Punct::Backslash),
-            '!' => self.consume()?.bang(),
-            '|' => self.consume()?.bar(),
-            ':' => self.consume()?.colon(),
-            ',' => self.consume()?.produce_op(Punct::Comma),
-            '.' => self.consume()?.dot(),
-            '=' => self.consume()?.equal(),
-            '`' => self.consume()?.produce_op(Punct::Grave),
-            '>' => self.consume()?.greater(),
-            '#' => self.consume()?.hash(),
-            '<' => self.consume()?.less(),
-            '-' => self.consume()?.minus(),
-            '+' => self.consume()?.plus(),
-            '?' => self.consume()?.produce_op(Punct::Question),
-            '%' => self.consume()?.rem(),
-            ';' => self.consume()?.produce_op(Punct::Semi),
-            '/' => self.consume()?.slash(),
-            '*' => self.consume()?.star(),
-            '~' => self.consume()?.produce_op(Punct::Tilde),
-            '^' => self.consume()?.xor(),
-            '0' => self.consume()?.int_with_base(),
-            '1'..='9' => self.digits::<10>(),
-            '"' => self.consume()?.string(),
-            '\'' => self.consume()?.character(),
-            '_' => self.identifier(),
-            i if is_xid_start(i) => self.identifier(),
-            e => {
-                let err = Err(Error::unexpected_char(e, self.line(), self.col()));
-                let _ = self.consume();
-                err
-            }
-        }
-    }
-    /// Returns the current line
-    pub fn line(&self) -> u32 {
-        self.start_loc.0
-    }
-    /// Returns the current column
-    pub fn col(&self) -> u32 {
-        self.start_loc.1
-    }
-    fn next(&mut self) -> LResult<char> {
-        let out = self.peek();
-        self.consume()?;
-        out
-    }
-    fn peek(&mut self) -> LResult<char> {
-        self.iter
-            .peek()
-            .copied()
-            .ok_or(Error::end_of_file(self.line(), self.col()))
-    }
-    fn produce(&mut self, kind: TokenKind, data: impl Into<TokenData>) -> LResult<Token> {
-        let loc = self.start_loc;
-        self.start_loc = self.current_loc;
-        self.start = self.current;
-        Ok(Token::new(kind, data, loc.0, loc.1))
-    }
-    fn produce_op(&mut self, kind: Punct) -> LResult<Token> {
-        self.produce(TokenKind::Punct(kind), ())
-    }
-    fn skip_whitespace(&mut self) -> &mut Self {
-        while let Ok(c) = self.peek() {
-            if !c.is_whitespace() {
-                break;
-            }
-            let _ = self.consume();
-        }
-        self.start = self.current;
-        self.start_loc = self.current_loc;
-        self
-    }
-    fn consume(&mut self) -> LResult<&mut Self> {
-        self.current += 1;
-        match self.iter.next() {
-            Some('\n') => {
-                let (line, col) = &mut self.current_loc;
-                *line += 1;
-                *col = 1;
-            }
-            Some(_) => self.current_loc.1 += 1,
-            None => Err(Error::end_of_file(self.line(), self.col()))?,
-        }
-        Ok(self)
-    }
-}
-/// Digraphs and trigraphs
-impl<'t> Lexer<'t> {
-    fn amp(&mut self) -> LResult<Token> {
-        match self.peek() {
-            Ok('&') => self.consume()?.produce_op(Punct::AmpAmp),
-            Ok('=') => self.consume()?.produce_op(Punct::AmpEq),
-            _ => self.produce_op(Punct::Amp),
-        }
-    }
-    fn bang(&mut self) -> LResult<Token> {
-        match self.peek() {
-            Ok('!') => self.consume()?.produce_op(Punct::BangBang),
-            Ok('=') => self.consume()?.produce_op(Punct::BangEq),
-            _ => self.produce_op(Punct::Bang),
-        }
-    }
-    fn bar(&mut self) -> LResult<Token> {
-        match self.peek() {
-            Ok('|') => self.consume()?.produce_op(Punct::BarBar),
-            Ok('=') => self.consume()?.produce_op(Punct::BarEq),
-            _ => self.produce_op(Punct::Bar),
-        }
-    }
-    fn colon(&mut self) -> LResult<Token> {
-        match self.peek() {
-            Ok(':') => self.consume()?.produce_op(Punct::ColonColon),
-            _ => self.produce_op(Punct::Colon),
-        }
-    }
-    fn dot(&mut self) -> LResult<Token> {
-        match self.peek() {
-            Ok('.') => {
-                if let Ok('=') = self.consume()?.peek() {
-                    self.consume()?.produce_op(Punct::DotDotEq)
-                } else {
-                    self.produce_op(Punct::DotDot)
-                }
-            }
-            _ => self.produce_op(Punct::Dot),
-        }
-    }
-    fn equal(&mut self) -> LResult<Token> {
-        match self.peek() {
-            Ok('=') => self.consume()?.produce_op(Punct::EqEq),
-            Ok('>') => self.consume()?.produce_op(Punct::FatArrow),
-            _ => self.produce_op(Punct::Eq),
-        }
-    }
-    fn greater(&mut self) -> LResult<Token> {
-        match self.peek() {
-            Ok('=') => self.consume()?.produce_op(Punct::GtEq),
-            Ok('>') => {
-                if let Ok('=') = self.consume()?.peek() {
-                    self.consume()?.produce_op(Punct::GtGtEq)
-                } else {
-                    self.produce_op(Punct::GtGt)
-                }
-            }
-            _ => self.produce_op(Punct::Gt),
-        }
-    }
-    fn hash(&mut self) -> LResult<Token> {
-        match self.peek() {
-            Ok('!') => self.consume()?.produce_op(Punct::HashBang),
-            _ => self.produce_op(Punct::Hash),
-        }
-    }
-    fn less(&mut self) -> LResult<Token> {
-        match self.peek() {
-            Ok('=') => self.consume()?.produce_op(Punct::LtEq),
-            Ok('<') => {
-                if let Ok('=') = self.consume()?.peek() {
-                    self.consume()?.produce_op(Punct::LtLtEq)
-                } else {
-                    self.produce_op(Punct::LtLt)
-                }
-            }
-            _ => self.produce_op(Punct::Lt),
-        }
-    }
-    fn minus(&mut self) -> LResult<Token> {
-        match self.peek() {
-            Ok('=') => self.consume()?.produce_op(Punct::MinusEq),
-            Ok('>') => self.consume()?.produce_op(Punct::Arrow),
-            _ => self.produce_op(Punct::Minus),
-        }
-    }
-    fn plus(&mut self) -> LResult<Token> {
-        match self.peek() {
-            Ok('=') => self.consume()?.produce_op(Punct::PlusEq),
-            _ => self.produce_op(Punct::Plus),
-        }
-    }
-    fn rem(&mut self) -> LResult<Token> {
-        match self.peek() {
-            Ok('=') => self.consume()?.produce_op(Punct::RemEq),
-            _ => self.produce_op(Punct::Rem),
-        }
-    }
-    fn slash(&mut self) -> LResult<Token> {
-        match self.peek() {
-            Ok('=') => self.consume()?.produce_op(Punct::SlashEq),
-            Ok('/') => self.consume()?.line_comment(),
-            Ok('*') => self.consume()?.block_comment(),
-            _ => self.produce_op(Punct::Slash),
-        }
-    }
-    fn star(&mut self) -> LResult<Token> {
-        match self.peek() {
-            Ok('=') => self.consume()?.produce_op(Punct::StarEq),
-            _ => self.produce_op(Punct::Star),
-        }
-    }
-    fn xor(&mut self) -> LResult<Token> {
-        match self.peek() {
-            Ok('=') => self.consume()?.produce_op(Punct::XorEq),
-            Ok('^') => self.consume()?.produce_op(Punct::XorXor),
-            _ => self.produce_op(Punct::Xor),
-        }
-    }
-}
-/// Comments
-impl<'t> Lexer<'t> {
-    fn line_comment(&mut self) -> LResult<Token> {
-        while Ok('\n') != self.peek() {
-            self.consume()?;
-        }
-        self.produce(Kind::Comment, ())
-    }
-    fn block_comment(&mut self) -> LResult<Token> {
-        while let Ok(c) = self.next() {
-            if '*' == c && Ok('/') == self.next() {
-                break;
-            }
-        }
-        self.produce(Kind::Comment, ())
-    }
-}
-/// Identifiers
-impl<'t> Lexer<'t> {
-    fn identifier(&mut self) -> LResult<Token> {
-        let mut out = String::from(self.xid_start()?);
-        while let Ok(c) = self.xid_continue() {
-            out.push(c)
-        }
-        if let Ok(keyword) = Kind::from_str(&out) {
-            self.produce(keyword, ())
-        } else {
-            self.produce(Kind::Identifier, TokenData::String(out))
-        }
-    }
-    fn xid_start(&mut self) -> LResult<char> {
-        match self.peek()? {
-            xid if xid == '_' || is_xid_start(xid) => {
-                self.consume()?;
-                Ok(xid)
-            }
-            bad => Err(Error::not_identifier(bad, self.line(), self.col())),
-        }
-    }
-    fn xid_continue(&mut self) -> LResult<char> {
-        match self.peek()? {
-            xid if is_xid_continue(xid) => {
-                self.consume()?;
-                Ok(xid)
-            }
-            bad => Err(Error::not_identifier(bad, self.line(), self.col())),
-        }
-    }
-}
-/// Integers
-impl<'t> Lexer<'t> {
-    fn int_with_base(&mut self) -> LResult<Token> {
-        match self.peek() {
-            Ok('x') => self.consume()?.digits::<16>(),
-            Ok('d') => self.consume()?.digits::<10>(),
-            Ok('o') => self.consume()?.digits::<8>(),
-            Ok('b') => self.consume()?.digits::<2>(),
-            Ok('0'..='9') => self.digits::<10>(),
-            _ => self.produce(Kind::Literal, 0),
-        }
-    }
-    fn digits<const B: u32>(&mut self) -> LResult<Token> {
-        let mut value = self.digit::<B>()? as u128;
-        while let Ok(true) = self.peek().as_ref().map(char::is_ascii_alphanumeric) {
-            value = value * B as u128 + self.digit::<B>()? as u128;
-        }
-        self.produce(Kind::Literal, value)
-    }
-    fn digit<const B: u32>(&mut self) -> LResult<u32> {
-        let digit = self.peek()?;
-        self.consume()?;
-        digit
-            .to_digit(B)
-            .ok_or(Error::invalid_digit(digit, self.line(), self.col()))
-    }
-}
-/// Strings and characters
-impl<'t> Lexer<'t> {
-    fn string(&mut self) -> LResult<Token> {
-        let mut value = String::new();
-        while '"'
-            != self
-                .peek()
-                .map_err(|e| e.mask_reason(Reason::UnmatchedDelimiters('"')))?
-        {
-            value.push(self.unescape()?)
-        }
-        self.consume()?.produce(Kind::Literal, value)
-    }
-    fn character(&mut self) -> LResult<Token> {
-        let out = self.unescape()?;
-        match self.peek()? {
-            '\'' => self.consume()?.produce(Kind::Literal, out),
-            _ => Err(Error::unmatched_delimiters('\'', self.line(), self.col())),
-        }
-    }
-    /// Unescape a single character
-    fn unescape(&mut self) -> LResult<char> {
-        match self.next() {
-            Ok('\\') => (),
-            other => return other,
-        }
-        Ok(match self.next()? {
-            'a' => '\x07',
-            'b' => '\x08',
-            'f' => '\x0c',
-            'n' => '\n',
-            'r' => '\r',
-            't' => '\t',
-            'x' => self.hex_escape()?,
-            'u' => self.unicode_escape()?,
-            '0' => '\0',
-            chr => chr,
-        })
-    }
-    /// unescape a single 2-digit hex escape
-    fn hex_escape(&mut self) -> LResult<char> {
-        let out = (self.digit::<16>()? << 4) + self.digit::<16>()?;
-        char::from_u32(out).ok_or(Error::bad_unicode(out, self.line(), self.col()))
-    }
-    /// unescape a single \u{} unicode escape
-    fn unicode_escape(&mut self) -> LResult<char> {
-        let mut out = 0;
-        let Ok('{') = self.peek() else {
-            return Err(Error::invalid_escape('u', self.line(), self.col()));
-        };
-        self.consume()?;
-        while let Ok(c) = self.peek() {
-            match c {
-                '}' => {
-                    self.consume()?;
-                    return char::from_u32(out).ok_or(Error::bad_unicode(
-                        out,
-                        self.line(),
-                        self.col(),
-                    ));
-                }
-                _ => out = (out << 4) + self.digit::<16>()?,
-            }
-        }
-        Err(Error::invalid_escape('u', self.line(), self.col()))
-    }
-}
-
-impl<'t> From<&Lexer<'t>> for Loc {
-    fn from(value: &Lexer<'t>) -> Self {
-        Loc(value.line(), value.col())
-    }
-}
-
-use error::{Error, LResult, Reason};
-pub mod error {
-    //! [Error] type for the [Lexer](super::Lexer)
-    use std::fmt::Display;
-
-    /// Result type with [Err] = [Error]
-    pub type LResult<T> = Result<T, Error>;
-    #[derive(Clone, Debug, PartialEq, Eq)]
-    pub struct Error {
-        pub reason: Reason,
-        pub line: u32,
-        pub col: u32,
-    }
-    /// The reason for the [Error]
-    #[derive(Clone, Copy, Debug, PartialEq, Eq)]
-    pub enum Reason {
-        /// Found an opening delimiter of type [char], but not the expected closing delimiter
-        UnmatchedDelimiters(char),
-        /// Found a character that doesn't belong to any [TokenKind](cl_token::TokenKind)
-        UnexpectedChar(char),
-        /// Found a character that's not valid in identifiers while looking for an identifier
-        NotIdentifier(char),
-        /// Found a character that's not valid in an escape sequence while looking for an escape
-        /// sequence
-        UnknownEscape(char),
-        /// Escape sequence contains invalid hexadecimal digit or unmatched braces
-        InvalidEscape(char),
-        /// Character is not a valid digit in the requested base
-        InvalidDigit(char),
-        /// Base conversion requested, but the base character was not in the set of known
-        /// characters
-        UnknownBase(char),
-        /// Unicode escape does not map to a valid unicode code-point
-        BadUnicode(u32),
-        /// Reached end of input
-        EndOfFile,
-    }
-    error_impl! {
-        unmatched_delimiters(c: char) => Reason::UnmatchedDelimiters(c),
-        unexpected_char(c: char) => Reason::UnexpectedChar(c),
-        not_identifier(c: char) => Reason::NotIdentifier(c),
-        unknown_escape(e: char) => Reason::UnknownEscape(e),
-        invalid_escape(e: char) => Reason::InvalidEscape(e),
-        invalid_digit(digit: char) => Reason::InvalidDigit(digit),
-        unknown_base(base: char) => Reason::UnknownBase(base),
-        bad_unicode(value: u32) => Reason::BadUnicode(value),
-        end_of_file => Reason::EndOfFile,
-    }
-    impl Error {
-        /// Changes the [Reason] of this error
-        pub(super) fn mask_reason(self, reason: Reason) -> Self {
-            Self { reason, ..self }
-        }
-        /// Returns the [Reason] for this error
-        pub fn reason(&self) -> &Reason {
-            &self.reason
-        }
-        /// Returns the (line, col) where the error happened
-        pub fn location(&self) -> (u32, u32) {
-            (self.line, self.col)
-        }
-    }
-    macro error_impl ($($fn:ident$(( $($p:ident: $t:ty),* ))? => $reason:expr),*$(,)?) {
-        #[allow(dead_code)]
-        impl Error {
-            $(pub(super) fn $fn ($($($p: $t),*,)? line: u32, col: u32) -> Self {
-                Self { reason: $reason, line, col }
-            })*
-        }
-    }
-    impl std::error::Error for Error {}
-    impl Display for Error {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            write!(f, "{}:{}: {}", self.line, self.col, self.reason)
-        }
-    }
-    impl Display for Reason {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            match self {
-                Reason::UnmatchedDelimiters(c) => write! {f, "Unmatched `{c}` in input"},
-                Reason::UnexpectedChar(c) => write!(f, "Character `{c}` not expected"),
-                Reason::NotIdentifier(c) => write!(f, "Character `{c}` not valid in identifiers"),
-                Reason::UnknownEscape(c) => write!(f, "`\\{c}` is not a known escape sequence"),
-                Reason::InvalidEscape(c) => write!(f, "Escape sequence `\\{c}`... is malformed"),
-                Reason::InvalidDigit(c) => write!(f, "`{c}` is not a valid digit"),
-                Reason::UnknownBase(c) => write!(f, "`0{c}`... is not a valid base"),
-                Reason::BadUnicode(c) => write!(f, "`{c}` is not a valid unicode code-point"),
-                Reason::EndOfFile => write!(f, "Reached end of input"),
-            }
-        }
-    }
-}

cl-repl/examples/typeck.rs

@@ -1,109 +0,0 @@
-use cl_lexer::Lexer;
-use cl_parser::Parser;
-use cl_repl::repline::{error::Error as RlError, Repline};
-use cl_typeck::{name_collector::NameCollector, project::Project};
-use std::error::Error;
-
-fn main() -> Result<(), Box<dyn Error>> {
-    let mut prj = Project::default();
-    let mut tcol = NameCollector::new(&mut prj);
-
-    println!(
-        "--- {} v{} 💪🦈 ---",
-        env!("CARGO_BIN_NAME"),
-        env!("CARGO_PKG_VERSION"),
-    );
-
-    read_and(
-        "\x1b[33m",
-        "cl>",
-        "? >",
-        |line| -> Result<_, Box<dyn Error>> {
-            if line.trim_start().is_empty() {
-                query(&tcol)?;
-                return Ok(Response::Deny);
-            }
-            let mut parser = Parser::new(Lexer::new(line));
-            let code = match parser.file() {
-                Ok(code) => code,
-                Err(e) => Err(e)?,
-            };
-            tcol.file(&code)?;
-            Ok(Response::Accept)
-        },
-    )
-}
-
-pub enum Response {
-    Accept,
-    Deny,
-    Break,
-}
-
-fn read_and(
-    color: &str,
-    begin: &str,
-    again: &str,
-    mut f: impl FnMut(&str) -> Result<Response, Box<dyn Error>>,
-) -> Result<(), Box<dyn Error>> {
-    let mut rl = Repline::new(color, begin, again);
-    loop {
-        let line = match rl.read() {
-            Err(RlError::CtrlC(_)) => break,
-            Err(RlError::CtrlD(line)) => {
-                rl.deny();
-                line
-            }
-            Ok(line) => line,
-            Err(e) => Err(e)?,
-        };
-        print!("\x1b[G\x1b[J");
-        match f(&line) {
-            Ok(Response::Accept) => rl.accept(),
-            Ok(Response::Deny) => rl.deny(),
-            Ok(Response::Break) => break,
-            Err(e) => print!("\x1b[40G\x1bJ\x1b[91m{e}\x1b[0m"),
-        }
-    }
-    Ok(())
-}
-
-fn query(prj: &Project) -> Result<(), Box<dyn Error>> {
-    use cl_typeck::{
-        definition::{Def, DefKind},
-        type_kind::TypeKind,
-    };
-    read_and("\x1b[35m", "qy>", "? >", |line| {
-        if line.trim_start().is_empty() {
-            return Ok(Response::Break);
-        }
-        match line {
-            "$all\n" => println!("{prj:#?}"),
-            _ => {
-                // parse it as a path, and convert the path into a borrowed path
-                let path = Parser::new(Lexer::new(line)).path()?;
-
-                let Some((type_id, path)) = prj.get_type((&path).into(), prj.module_root) else {
-                    return Ok(Response::Deny);
-                };
-                let Def { name, vis, meta: _, kind, source: _, module } = &prj[type_id];
-                match (kind, prj.get_value(path, type_id)) {
-                    (_, Some((val, path))) => {
-                        println!("value {}; {path}\n{:#?}", usize::from(val), prj[val])
-                    }
-                    (DefKind::Type(TypeKind::Module), None) => println!(
-                        "{vis}mod \"{name}\" (#{}); {path}\n{:#?}",
-                        usize::from(type_id),
-                        module
-                    ),
-                    (_, None) => println!(
-                        "type {name}(#{}); {path}\n{:#?}",
-                        usize::from(type_id),
-                        prj.pool[type_id]
-                    ),
-                };
-            }
-        }
-        Ok(Response::Accept)
-    })
-}

cl-repl/src/bin/conlang.rs

@@ -1,13 +0,0 @@
-use cl_repl::{cli::run, tools::is_terminal};
-use std::error::Error;
-
-fn main() -> Result<(), Box<dyn Error>> {
-    if is_terminal() {
-        println!(
-            "--- {} v{} 💪🦈 ---",
-            env!("CARGO_BIN_NAME"),
-            env!("CARGO_PKG_VERSION"),
-        );
-    }
-    run(argh::from_env())
-}

cl-repl/src/lib.rs

@@ -1,462 +0,0 @@
-//! Utilities for cl-frontend
-//!
-//! # TODO
-//! - [ ] Readline-like line editing
-//! - [ ] Raw mode?
-#![warn(clippy::all)]
-
-pub mod ansi {
-    // ANSI color escape sequences
-    pub const ANSI_RED: &str = "\x1b[31m";
-    pub const ANSI_GREEN: &str = "\x1b[32m"; // the color of type checker mode
-    pub const ANSI_CYAN: &str = "\x1b[36m";
-    // pub const ANSI_BRIGHT_GREEN: &str = "\x1b[92m";
-    pub const ANSI_BRIGHT_BLUE: &str = "\x1b[94m";
-    pub const ANSI_BRIGHT_MAGENTA: &str = "\x1b[95m";
-    // const ANSI_BRIGHT_CYAN: &str = "\x1b[96m";
-    pub const ANSI_RESET: &str = "\x1b[0m";
-    pub const ANSI_OUTPUT: &str = "\x1b[38;5;117m";
-
-    pub const ANSI_CLEAR_LINES: &str = "\x1b[G\x1b[J";
-}
-
-pub mod args {
-    use crate::tools::is_terminal;
-    use argh::FromArgs;
-    use std::{path::PathBuf, str::FromStr};
-
-    /// The Conlang prototype debug interface
-    #[derive(Clone, Debug, FromArgs, PartialEq, Eq, PartialOrd, Ord)]
-    pub struct Args {
-        /// the main source file
-        #[argh(positional)]
-        pub file: Option<PathBuf>,
-
-        /// files to include
-        #[argh(option, short = 'I')]
-        pub include: Vec<PathBuf>,
-
-        /// the Repl mode to start in
-        #[argh(option, short = 'm', default = "Default::default()")]
-        pub mode: Mode,
-
-        /// whether to start the repl (`true` or `false`)
-        #[argh(option, short = 'r', default = "is_terminal()")]
-        pub repl: bool,
-    }
-
-    /// The CLI's operating mode
-    #[derive(Clone, Copy, Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
-    pub enum Mode {
-        Tokenize,
-        Beautify,
-        #[default]
-        Interpret,
-    }
-
-    impl Mode {
-        pub fn ansi_color(self) -> &'static str {
-            use super::ansi::*;
-            match self {
-                Mode::Tokenize => ANSI_BRIGHT_BLUE,
-                Mode::Beautify => ANSI_BRIGHT_MAGENTA,
-                // Mode::Resolve => ANSI_GREEN,
-                Mode::Interpret => ANSI_CYAN,
-            }
-        }
-    }
-
-    impl FromStr for Mode {
-        type Err = &'static str;
-        fn from_str(s: &str) -> Result<Self, &'static str> {
-            Ok(match s {
-                "i" | "interpret" | "r" | "run" => Mode::Interpret,
-                "b" | "beautify" | "p" | "pretty" => Mode::Beautify,
-                // "r" | "resolve" | "typecheck" | "type" => Mode::Resolve,
-                "t" | "tokenize" | "token" => Mode::Tokenize,
-                _ => Err("Recognized modes are: 'r' \"run\", 'p' \"pretty\", 't' \"token\"")?,
-            })
-        }
-    }
-}
-
-pub mod program {
-    use cl_interpret::{
-        env::Environment, error::IResult, interpret::Interpret, temp_type_impl::ConValue,
-    };
-
-    use cl_ast::{self as ast, format::*};
-    use cl_lexer::Lexer;
-    use cl_parser::{error::PResult, Parser};
-    // use conlang::resolver::{error::TyResult, Resolver};
-    use std::{fmt::Display, io::Write};
-
-    pub struct Parsable;
-
-    pub enum Parsed {
-        File(ast::File),
-        Stmt(ast::Stmt),
-        Expr(ast::Expr),
-    }
-
-    pub struct Program<'t, Variant> {
-        text: &'t str,
-        data: Variant,
-    }
-    impl<'t, V> Program<'t, V> {
-        pub fn lex(&self) -> Lexer {
-            Lexer::new(self.text)
-        }
-    }
-
-    impl<'t> Program<'t, Parsable> {
-        pub fn new(text: &'t str) -> Self {
-            Self { text, data: Parsable }
-        }
-        pub fn parse(self) -> PResult<Program<'t, Parsed>> {
-            self.parse_file().or_else(|_| self.parse_stmt())
-        }
-        pub fn parse_expr(&self) -> PResult<Program<'t, Parsed>> {
-            Ok(Program { data: Parsed::Expr(Parser::new(self.lex()).expr()?), text: self.text })
-        }
-        pub fn parse_stmt(&self) -> PResult<Program<'t, Parsed>> {
-            Ok(Program { data: Parsed::Stmt(Parser::new(self.lex()).stmt()?), text: self.text })
-        }
-        pub fn parse_file(&self) -> PResult<Program<'t, Parsed>> {
-            Ok(Program { data: Parsed::File(Parser::new(self.lex()).file()?), text: self.text })
-        }
-    }
-
-    impl<'t> Program<'t, Parsed> {
-        pub fn debug(&self) {
-            match &self.data {
-                Parsed::File(v) => eprintln!("{v:?}"),
-                Parsed::Stmt(v) => eprintln!("{v:?}"),
-                Parsed::Expr(v) => eprintln!("{v:?}"),
-            }
-        }
-        pub fn print(&self) {
-            let mut f = std::io::stdout().pretty();
-            let _ = match &self.data {
-                Parsed::File(v) => writeln!(f, "{v}"),
-                Parsed::Stmt(v) => writeln!(f, "{v}"),
-                Parsed::Expr(v) => writeln!(f, "{v}"),
-            };
-            // println!("{self}")
-        }
-
-        pub fn run(&self, env: &mut Environment) -> IResult<ConValue> {
-            match &self.data {
-                Parsed::File(v) => v.interpret(env),
-                Parsed::Stmt(v) => v.interpret(env),
-                Parsed::Expr(v) => v.interpret(env),
-            }
-        }
-
-        // pub fn resolve(&mut self, resolver: &mut Resolver) -> TyResult<()> {
-        //     match &mut self.data {
-        //         Parsed::Program(start) => start.resolve(resolver),
-        //         Parsed::Expr(expr) => expr.resolve(resolver),
-        //     }
-        //     .map(|ty| println!("{ty}"))
-        // }
-    }
-
-    impl<'t> Display for Program<'t, Parsed> {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            match &self.data {
-                Parsed::File(v) => write!(f, "{v}"),
-                Parsed::Stmt(v) => write!(f, "{v}"),
-                Parsed::Expr(v) => write!(f, "{v}"),
-            }
-        }
-    }
-}
-
-pub mod cli {
-    //! Implement's the command line interface
-    use crate::{
-        args::{Args, Mode},
-        program::{Parsable, Program},
-        repl::Repl,
-        tools::print_token,
-    };
-    use cl_interpret::{env::Environment, temp_type_impl::ConValue};
-    use cl_lexer::Lexer;
-    use cl_parser::Parser;
-    use std::{error::Error, path::Path};
-
-    /// Run the command line interface
-    pub fn run(args: Args) -> Result<(), Box<dyn Error>> {
-        let Args { file, include, mode, repl } = args;
-
-        let mut env = Environment::new();
-        for path in include {
-            load_file(&mut env, path)?;
-        }
-
-        if repl {
-            if let Some(file) = file {
-                load_file(&mut env, file)?;
-            }
-            Repl::with_env(mode, env).repl()
-        } else {
-            let code = match &file {
-                Some(file) => std::fs::read_to_string(file)?,
-                None => std::io::read_to_string(std::io::stdin())?,
-            };
-            let code = Program::new(&code);
-
-            match mode {
-                Mode::Tokenize => tokenize(code, file),
-                Mode::Beautify => beautify(code),
-                Mode::Interpret => interpret(code, &mut env),
-            }?;
-        }
-        Ok(())
-    }
-
-    fn load_file(
-        env: &mut Environment,
-        path: impl AsRef<Path>,
-    ) -> Result<ConValue, Box<dyn Error>> {
-        let file = std::fs::read_to_string(path)?;
-        let code = Parser::new(Lexer::new(&file)).file()?;
-        env.eval(&code).map_err(Into::into)
-    }
-
-    fn tokenize(
-        code: Program<Parsable>,
-        path: Option<impl AsRef<Path>>,
-    ) -> Result<(), Box<dyn Error>> {
-        for token in code.lex() {
-            if let Some(ref path) = path {
-                print!("{}:", path.as_ref().display());
-            }
-            match token {
-                Ok(token) => print_token(&token),
-                Err(e) => println!("{e}"),
-            }
-        }
-        Ok(())
-    }
-
-    fn beautify(code: Program<Parsable>) -> Result<(), Box<dyn Error>> {
-        code.parse()?.print();
-        Ok(())
-    }
-
-    fn interpret(code: Program<Parsable>, env: &mut Environment) -> Result<(), Box<dyn Error>> {
-        match code.parse()?.run(env)? {
-            ConValue::Empty => {}
-            ret => println!("{ret}"),
-        }
-        if env.get("main").is_ok() {
-            match env.call("main", &[])? {
-                ConValue::Empty => {}
-                ret => println!("{ret}"),
-            }
-        }
-        Ok(())
-    }
-}
-
-pub mod repl {
-    use crate::{
-        ansi::*,
-        args::Mode,
-        program::{Parsable, Parsed, Program},
-        tools::print_token,
-    };
-    use cl_interpret::{env::Environment, temp_type_impl::ConValue};
-    use std::fmt::Display;
-
-    /// Implements the interactive interpreter
-    #[derive(Clone, Debug)]
-    pub struct Repl {
-        prompt_again: &'static str, // " ?>"
-        prompt_begin: &'static str, // "cl>"
-        prompt_error: &'static str, // "! >"
-        prompt_succs: &'static str, // " ->"
-        env: Environment,
-        mode: Mode,
-    }
-
-    impl Default for Repl {
-        fn default() -> Self {
-            Self {
-                prompt_begin: "cl>",
-                prompt_again: " ?>",
-                prompt_error: "! >",
-                prompt_succs: " =>",
-                env: Default::default(),
-                mode: Default::default(),
-            }
-        }
-    }
-
-    /// Prompt functions
-    impl Repl {
-        pub fn prompt_result<T: Display, E: Display>(&self, res: Result<T, E>) {
-            match &res {
-                Ok(v) => self.prompt_succs(v),
-                Err(e) => self.prompt_error(e),
-            }
-        }
-        pub fn prompt_error(&self, err: &impl Display) {
-            let Self { prompt_error: prompt, .. } = self;
-            println!("{ANSI_CLEAR_LINES}{ANSI_RED}{prompt} {err}{ANSI_RESET}")
-        }
-        pub fn prompt_succs(&self, value: &impl Display) {
-            let Self { prompt_succs: _prompt, .. } = self;
-            println!("{ANSI_GREEN}{value}{ANSI_RESET}")
-        }
-        /// Resets the cursor to the start of the line, clears the terminal,
-        /// and sets the output color
-        pub fn begin_output(&self) {
-            print!("{ANSI_CLEAR_LINES}{ANSI_OUTPUT}")
-        }
-        pub fn clear_line(&self) {}
-    }
-    /// The actual REPL
-    impl Repl {
-        /// Constructs a new [Repl] with the provided [Mode]
-        pub fn new(mode: Mode) -> Self {
-            Self { mode, ..Default::default() }
-        }
-        /// Constructs a new [Repl] with the provided [Mode] and [Environment]
-        pub fn with_env(mode: Mode, env: Environment) -> Self {
-            Self { mode, env, ..Default::default() }
-        }
-        /// Runs the main REPL loop
-        pub fn repl(&mut self) {
-            use crate::repline::{error::Error, Repline};
-
-            let mut rl = Repline::new(self.mode.ansi_color(), self.prompt_begin, self.prompt_again);
-            fn clear_line() {
-                print!("\x1b[G\x1b[J");
-            }
-            loop {
-                let buf = match rl.read() {
-                    Ok(buf) => buf,
-                    // Ctrl-C: break if current line is empty
-                    Err(Error::CtrlC(buf)) => {
-                        if buf.is_empty() || buf.ends_with('\n') {
-                            return;
-                        }
-                        rl.accept();
-                        println!("Cancelled. (Press Ctrl+C again to quit.)");
-                        continue;
-                    }
-                    // Ctrl-D: reset input, and parse it for errors
-                    Err(Error::CtrlD(buf)) => {
-                        rl.deny();
-                        if let Err(e) = Program::new(&buf).parse() {
-                            clear_line();
-                            self.prompt_error(&e);
-                        }
-                        continue;
-                    }
-                    Err(e) => {
-                        self.prompt_error(&e);
-                        return;
-                    }
-                };
-
-                self.begin_output();
-                if self.command(&buf) {
-                    rl.deny();
-                    rl.set_color(self.mode.ansi_color());
-                    continue;
-                }
-                let code = Program::new(&buf);
-                if self.mode == Mode::Tokenize {
-                    self.tokenize(&code);
-                    rl.deny();
-                    continue;
-                }
-                match code.lex().into_iter().find(|l| l.is_err()) {
-                    None => {}
-                    Some(Ok(_)) => unreachable!(),
-                    Some(Err(error)) => {
-                        rl.deny();
-                        self.prompt_error(&error);
-                        continue;
-                    }
-                }
-                if let Ok(mut code) = code.parse() {
-                    rl.accept();
-                    self.dispatch(&mut code);
-                }
-            }
-        }
-
-        fn help(&self) {
-            println!(
-                "Commands:\n- $tokens\n    Tokenize Mode:\n    Outputs information derived by the Lexer\n- $pretty\n    Beautify Mode:\n    Pretty-prints the input\n- $type\n    Resolve Mode:\n    Attempts variable resolution and type-checking on the input\n- $run\n    Interpret Mode:\n    Interprets the input using Conlang\'s work-in-progress interpreter\n- $mode\n    Prints the current mode\n- $help\n    Prints this help message"
-            );
-        }
-        fn command(&mut self, line: &str) -> bool {
-            let Some(line) = line.trim().strip_prefix('$') else {
-                return false;
-            };
-            if let Ok(mode) = line.parse() {
-                self.mode = mode;
-            } else {
-                match line {
-                    "$run" => self.mode = Mode::Interpret,
-                    "mode" => println!("{:?} Mode", self.mode),
-                    "help" => self.help(),
-                    _ => return false,
-                }
-            }
-            true
-        }
-        /// Dispatches calls to repl functions based on the program
-        fn dispatch(&mut self, code: &mut Program<Parsed>) {
-            match self.mode {
-                Mode::Tokenize => {}
-                Mode::Beautify => self.beautify(code),
-                Mode::Interpret => self.interpret(code),
-            }
-        }
-        fn tokenize(&mut self, code: &Program<Parsable>) {
-            for token in code.lex() {
-                match token {
-                    Ok(token) => print_token(&token),
-                    Err(e) => println!("{e}"),
-                }
-            }
-        }
-        fn interpret(&mut self, code: &Program<Parsed>) {
-            match code.run(&mut self.env) {
-                Ok(ConValue::Empty) => {}
-                res => self.prompt_result(res),
-            }
-        }
-        fn beautify(&mut self, code: &Program<Parsed>) {
-            code.print()
-        }
-    }
-}
-
-pub mod tools {
-    use cl_token::Token;
-    use std::io::IsTerminal;
-    /// Prints a token in the particular way cl-repl does
-    pub fn print_token(t: &Token) {
-        println!(
-            "{:02}:{:02}: {:#19} │{}│",
-            t.line(),
-            t.col(),
-            t.ty(),
-            t.data(),
-        )
-    }
-    /// gets whether stdin AND stdout are a terminal, for pipelining
-    pub fn is_terminal() -> bool {
-        std::io::stdin().is_terminal() && std::io::stdout().is_terminal()
-    }
-}
-
-pub mod repline;

cl-repl/src/repline.rs

@@ -1,636 +0,0 @@
-//! A small pseudo-multiline editing library
-// #![allow(unused)]
-
-pub mod error {
-    /// Result type for Repline
-    pub type ReplResult<T> = std::result::Result<T, Error>;
-    /// Borrowed error (does not implement [Error](std::error::Error)!)
-    #[derive(Debug)]
-    pub enum Error {
-        /// User broke with Ctrl+C
-        CtrlC(String),
-        /// User broke with Ctrl+D
-        CtrlD(String),
-        /// Invalid unicode codepoint
-        BadUnicode(u32),
-        /// Error came from [std::io]
-        IoFailure(std::io::Error),
-        /// End of input
-        EndOfInput,
-    }
-
-    impl std::error::Error for Error {}
-    impl std::fmt::Display for Error {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            match self {
-                Error::CtrlC(_) => write!(f, "Ctrl+C"),
-                Error::CtrlD(_) => write!(f, "Ctrl+D"),
-                Error::BadUnicode(u) => write!(f, "0x{u:x} is not a valid unicode codepoint"),
-                Error::IoFailure(s) => write!(f, "{s}"),
-                Error::EndOfInput => write!(f, "End of input"),
-            }
-        }
-    }
-    impl From<std::io::Error> for Error {
-        fn from(value: std::io::Error) -> Self {
-            Self::IoFailure(value)
-        }
-    }
-}
-
-pub mod ignore {
-    //! Does nothing, universally.
-    //!
-    //! Introduces the [Ignore] trait, and its singular function, [ignore](Ignore::ignore),
-    //! which does nothing.
-    impl<T> Ignore for T {}
-    /// Does nothing
-    ///
-    /// # Examples
-    /// ```rust
-    /// #![deny(unused_must_use)]
-    /// # use cl_repl::repline::ignore::Ignore;
-    /// ().ignore();
-    /// Err::<(), &str>("Foo").ignore();
-    /// Some("Bar").ignore();
-    /// 42.ignore();
-    ///
-    /// #[must_use]
-    /// fn the_meaning() -> usize {
-    ///     42
-    /// }
-    /// the_meaning().ignore();
-    /// ```
-    pub trait Ignore {
-        /// Does nothing
-        fn ignore(&self) {}
-    }
-}
-
-pub mod chars {
-    //! Converts an <code>[Iterator]<Item = [u8]></code> into an
-    //! <code>[Iterator]<Item = [char]></code>
-
-    use super::error::*;
-
-    /// Converts an <code>[Iterator]<Item = [u8]></code> into an
-    /// <code>[Iterator]<Item = [char]></code>
-    #[derive(Clone, Debug)]
-    pub struct Chars<I: Iterator<Item = u8>>(pub I);
-    impl<I: Iterator<Item = u8>> Chars<I> {
-        pub fn new(bytes: I) -> Self {
-            Self(bytes)
-        }
-    }
-    impl<I: Iterator<Item = u8>> Iterator for Chars<I> {
-        type Item = ReplResult<char>;
-        fn next(&mut self) -> Option<Self::Item> {
-            let Self(bytes) = self;
-            let start = bytes.next()? as u32;
-            let (mut out, count) = match start {
-                start if start & 0x80 == 0x00 => (start, 0), // ASCII valid range
-                start if start & 0xe0 == 0xc0 => (start & 0x1f, 1), // 1 continuation byte
-                start if start & 0xf0 == 0xe0 => (start & 0x0f, 2), // 2 continuation bytes
-                start if start & 0xf8 == 0xf0 => (start & 0x07, 3), // 3 continuation bytes
-                _ => return None,
-            };
-            for _ in 0..count {
-                let cont = bytes.next()? as u32;
-                if cont & 0xc0 != 0x80 {
-                    return None;
-                }
-                out = out << 6 | (cont & 0x3f);
-            }
-            Some(char::from_u32(out).ok_or(Error::BadUnicode(out)))
-        }
-    }
-}
-
-pub mod flatten {
-    //! Flattens an [Iterator] returning [`Result<T, E>`](Result) or [`Option<T>`](Option)
-    //! into a *non-[FusedIterator](std::iter::FusedIterator)* over `T`
-
-    /// Flattens an [Iterator] returning [`Result<T, E>`](Result) or [`Option<T>`](Option)
-    /// into a *non-[FusedIterator](std::iter::FusedIterator)* over `T`
-    pub struct Flatten<T, I: Iterator<Item = T>>(pub I);
-    impl<T, E, I: Iterator<Item = Result<T, E>>> Iterator for Flatten<Result<T, E>, I> {
-        type Item = T;
-        fn next(&mut self) -> Option<Self::Item> {
-            self.0.next()?.ok()
-        }
-    }
-    impl<T, I: Iterator<Item = Option<T>>> Iterator for Flatten<Option<T>, I> {
-        type Item = T;
-        fn next(&mut self) -> Option<Self::Item> {
-            self.0.next()?
-        }
-    }
-}
-
-pub mod raw {
-    //! Sets the terminal to [`raw`] mode for the duration of the returned object's lifetime.
-
-    /// Sets the terminal to raw mode for the duration of the returned object's lifetime.
-    pub fn raw() -> impl Drop {
-        Raw::default()
-    }
-    struct Raw();
-    impl Default for Raw {
-        fn default() -> Self {
-            std::thread::yield_now();
-            crossterm::terminal::enable_raw_mode()
-                .expect("should be able to transition into raw mode");
-            Raw()
-        }
-    }
-    impl Drop for Raw {
-        fn drop(&mut self) {
-            crossterm::terminal::disable_raw_mode()
-                .expect("should be able to transition out of raw mode");
-            // std::thread::yield_now();
-        }
-    }
-}
-
-mod out {
-    #![allow(unused)]
-    use std::io::{Result, Write};
-
-    /// A [Writer](Write) that flushes after every wipe
-    #[derive(Clone, Debug)]
-    pub(super) struct EagerWriter<W: Write> {
-        out: W,
-    }
-    impl<W: Write> EagerWriter<W> {
-        pub fn new(writer: W) -> Self {
-            Self { out: writer }
-        }
-    }
-    impl<W: Write> Write for EagerWriter<W> {
-        fn write(&mut self, buf: &[u8]) -> Result<usize> {
-            let out = self.out.write(buf)?;
-            self.out.flush()?;
-            Ok(out)
-        }
-        fn flush(&mut self) -> Result<()> {
-            self.out.flush()
-        }
-    }
-}
-
-use self::{chars::Chars, editor::Editor, error::*, flatten::Flatten, ignore::Ignore, raw::raw};
-use std::{
-    collections::VecDeque,
-    io::{stdout, Bytes, Read, Result, Write},
-};
-
-pub struct Repline<'a, R: Read> {
-    input: Chars<Flatten<Result<u8>, Bytes<R>>>,
-
-    history: VecDeque<String>, // previous lines
-    hindex: usize,             // current index into the history buffer
-
-    ed: Editor<'a>, // the current line buffer
-}
-
-impl<'a, R: Read> Repline<'a, R> {
-    /// Constructs a [Repline] with the given [Reader](Read), color, begin, and again prompts.
-    pub fn with_input(input: R, color: &'a str, begin: &'a str, again: &'a str) -> Self {
-        Self {
-            input: Chars(Flatten(input.bytes())),
-            history: Default::default(),
-            hindex: 0,
-            ed: Editor::new(color, begin, again),
-        }
-    }
-    /// Set the terminal prompt color
-    pub fn set_color(&mut self, color: &'a str) {
-        self.ed.color = color
-    }
-    /// Reads in a line, and returns it for validation
-    pub fn read(&mut self) -> ReplResult<String> {
-        const INDENT: &str = "    ";
-        let mut stdout = stdout().lock();
-        let stdout = &mut stdout;
-        let _make_raw = raw();
-        // self.ed.begin_frame(stdout)?;
-        // self.ed.redraw_frame(stdout)?;
-        self.ed.print_head(stdout)?;
-        loop {
-            stdout.flush()?;
-            match self.input.next().ok_or(Error::EndOfInput)?? {
-                // Ctrl+C: End of Text. Immediately exits.
-                // Ctrl+D: End of Transmission. Ends the current line.
-                '\x03' => {
-                    drop(_make_raw);
-                    writeln!(stdout)?;
-                    return Err(Error::CtrlC(self.ed.to_string()));
-                }
-                '\x04' => {
-                    drop(_make_raw);
-                    writeln!(stdout)?;
-                    return Err(Error::CtrlD(self.ed.to_string()));
-                }
-                // Tab: extend line by 4 spaces
-                '\t' => {
-                    self.ed.extend(INDENT.chars(), stdout)?;
-                }
-                // ignore newlines, process line feeds. Not sure how cross-platform this is.
-                '\n' => {}
-                '\r' => {
-                    self.ed.push('\n', stdout)?;
-                    return Ok(self.ed.to_string());
-                }
-                // Escape sequence
-                '\x1b' => self.escape(stdout)?,
-                // backspace
-                '\x08' | '\x7f' => {
-                    let ed = &mut self.ed;
-                    if ed.ends_with(INDENT.chars()) {
-                        for _ in 0..INDENT.len() {
-                            ed.pop(stdout)?;
-                        }
-                    } else {
-                        ed.pop(stdout)?;
-                    }
-                }
-                c if c.is_ascii_control() => {
-                    if cfg!(debug_assertions) {
-                        eprint!("\\x{:02x}", c as u32);
-                    }
-                }
-                c => {
-                    self.ed.push(c, stdout)?;
-                }
-            }
-        }
-    }
-    /// Handle ANSI Escape
-    fn escape<W: Write>(&mut self, w: &mut W) -> ReplResult<()> {
-        match self.input.next().ok_or(Error::EndOfInput)?? {
-            '[' => self.csi(w)?,
-            'O' => todo!("Process alternate character mode"),
-            other => self.ed.extend(['\x1b', other], w)?,
-        }
-        Ok(())
-    }
-    /// Handle ANSI Control Sequence Introducer
-    fn csi<W: Write>(&mut self, w: &mut W) -> ReplResult<()> {
-        match self.input.next().ok_or(Error::EndOfInput)?? {
-            'A' => {
-                self.hindex = self.hindex.saturating_sub(1);
-                self.restore_history(w)?
-            }
-            'B' => {
-                self.hindex = self
-                    .hindex
-                    .saturating_add(1)
-                    .min(self.history.len().saturating_sub(1));
-                self.restore_history(w)?
-            }
-            'C' => self.ed.cursor_forward(1, w)?,
-            'D' => self.ed.cursor_back(1, w)?,
-            'H' => self.ed.home(w)?,
-            'F' => self.ed.end(w)?,
-            '3' => {
-                if let '~' = self.input.next().ok_or(Error::EndOfInput)?? {
-                    self.ed.delete(w).ignore()
-                }
-            }
-            other => {
-                if cfg!(debug_assertions) {
-                    eprint!("{}", other.escape_unicode());
-                }
-            }
-        }
-        Ok(())
-    }
-    /// Restores the currently selected history
-    pub fn restore_history<W: Write>(&mut self, w: &mut W) -> ReplResult<()> {
-        let Self { history, hindex, ed, .. } = self;
-        if !(0..history.len()).contains(hindex) {
-            return Ok(());
-        };
-        ed.undraw(w)?;
-        ed.clear();
-        ed.print_head(w)?;
-        ed.extend(
-            history
-                .get(*hindex)
-                .expect("history should contain index")
-                .chars(),
-            w,
-        )
-    }
-
-    /// Append line to history and clear it
-    pub fn accept(&mut self) {
-        self.history_append(self.ed.iter().collect());
-        self.ed.clear();
-        self.hindex = self.history.len();
-    }
-    /// Append line to history
-    pub fn history_append(&mut self, mut buf: String) {
-        while buf.ends_with(char::is_whitespace) {
-            buf.pop();
-        }
-        if !self.history.contains(&buf) {
-            self.history.push_back(buf)
-        }
-        while self.history.len() > 20 {
-            self.history.pop_front();
-        }
-    }
-    /// Clear the line
-    pub fn deny(&mut self) {
-        self.ed.clear()
-    }
-}
-
-impl<'a> Repline<'a, std::io::Stdin> {
-    pub fn new(color: &'a str, begin: &'a str, again: &'a str) -> Self {
-        Self::with_input(std::io::stdin(), color, begin, again)
-    }
-}
-
-pub mod editor {
-    use crossterm::{cursor::*, execute, queue, style::*, terminal::*};
-    use std::{collections::VecDeque, fmt::Display, io::Write};
-
-    use super::error::{Error, ReplResult};
-
-    fn is_newline(c: &char) -> bool {
-        *c == '\n'
-    }
-
-    fn write_chars<'a, W: Write>(
-        c: impl IntoIterator<Item = &'a char>,
-        w: &mut W,
-    ) -> std::io::Result<()> {
-        for c in c {
-            write!(w, "{c}")?;
-        }
-        Ok(())
-    }
-
-    #[derive(Debug)]
-    pub struct Editor<'a> {
-        head: VecDeque<char>,
-        tail: VecDeque<char>,
-
-        pub color: &'a str,
-        begin: &'a str,
-        again: &'a str,
-    }
-
-    impl<'a> Editor<'a> {
-        pub fn new(color: &'a str, begin: &'a str, again: &'a str) -> Self {
-            Self { head: Default::default(), tail: Default::default(), color, begin, again }
-        }
-        pub fn iter(&self) -> impl Iterator<Item = &char> {
-            self.head.iter()
-        }
-        pub fn undraw<W: Write>(&self, w: &mut W) -> ReplResult<()> {
-            let Self { head, .. } = self;
-            match head.iter().copied().filter(is_newline).count() {
-                0 => write!(w, "\x1b[0G"),
-                lines => write!(w, "\x1b[{}F", lines),
-            }?;
-            queue!(w, Clear(ClearType::FromCursorDown))?;
-            // write!(w, "\x1b[0J")?;
-            Ok(())
-        }
-        pub fn redraw<W: Write>(&self, w: &mut W) -> ReplResult<()> {
-            let Self { head, tail, color, begin, again } = self;
-            write!(w, "{color}{begin}\x1b[0m ")?;
-            // draw head
-            for c in head {
-                match c {
-                    '\n' => write!(w, "\r\n{color}{again}\x1b[0m "),
-                    _ => w.write_all({ *c as u32 }.to_le_bytes().as_slice()),
-                }?
-            }
-            // save cursor
-            execute!(w, SavePosition)?;
-            // draw tail
-            for c in tail {
-                match c {
-                    '\n' => write!(w, "\r\n{color}{again}\x1b[0m "),
-                    _ => write!(w, "{c}"),
-                }?
-            }
-            // restore cursor
-            execute!(w, RestorePosition)?;
-            Ok(())
-        }
-        pub fn prompt<W: Write>(&self, w: &mut W) -> ReplResult<()> {
-            let Self { head, color, begin, again, .. } = self;
-            queue!(
-                w,
-                MoveToColumn(0),
-                Print(color),
-                Print(if head.is_empty() { begin } else { again }),
-                ResetColor,
-                Print(' '),
-            )?;
-            Ok(())
-        }
-        pub fn print_head<W: Write>(&self, w: &mut W) -> ReplResult<()> {
-            self.prompt(w)?;
-            write_chars(
-                self.head.iter().skip(
-                    self.head
-                        .iter()
-                        .rposition(is_newline)
-                        .unwrap_or(self.head.len())
-                        + 1,
-                ),
-                w,
-            )?;
-            Ok(())
-        }
-        pub fn print_tail<W: Write>(&self, w: &mut W) -> ReplResult<()> {
-            let Self { tail, .. } = self;
-            queue!(w, SavePosition, Clear(ClearType::UntilNewLine))?;
-            write_chars(tail.iter().take_while(|&c| !is_newline(c)), w)?;
-            queue!(w, RestorePosition)?;
-            Ok(())
-        }
-        pub fn push<W: Write>(&mut self, c: char, w: &mut W) -> ReplResult<()> {
-            // Tail optimization: if the tail is empty,
-            //we don't have to undraw and redraw on newline
-            if self.tail.is_empty() {
-                self.head.push_back(c);
-                match c {
-                    '\n' => {
-                        write!(w, "\r\n")?;
-                        self.print_head(w)?;
-                    }
-                    c => {
-                        queue!(w, Print(c))?;
-                    }
-                };
-                return Ok(());
-            }
-
-            if '\n' == c {
-                self.undraw(w)?;
-            }
-            self.head.push_back(c);
-            match c {
-                '\n' => self.redraw(w)?,
-                _ => {
-                    write!(w, "{c}")?;
-                    self.print_tail(w)?;
-                }
-            }
-            Ok(())
-        }
-        pub fn pop<W: Write>(&mut self, w: &mut W) -> ReplResult<Option<char>> {
-            if let Some('\n') = self.head.back() {
-                self.undraw(w)?;
-            }
-            let c = self.head.pop_back();
-            // if the character was a newline, we need to go back a line
-            match c {
-                Some('\n') => self.redraw(w)?,
-                Some(_) => {
-                    // go back a char
-                    queue!(w, MoveLeft(1), Print(' '), MoveLeft(1))?;
-                    self.print_tail(w)?;
-                }
-                None => {}
-            }
-            Ok(c)
-        }
-
-        pub fn extend<T: IntoIterator<Item = char>, W: Write>(
-            &mut self,
-            iter: T,
-            w: &mut W,
-        ) -> ReplResult<()> {
-            for c in iter {
-                self.push(c, w)?;
-            }
-            Ok(())
-        }
-        pub fn restore(&mut self, s: &str) {
-            self.clear();
-            self.head.extend(s.chars())
-        }
-        pub fn clear(&mut self) {
-            self.head.clear();
-            self.tail.clear();
-        }
-        pub fn delete<W: Write>(&mut self, w: &mut W) -> ReplResult<char> {
-            match self.tail.front() {
-                Some('\n') => {
-                    self.undraw(w)?;
-                    let out = self.tail.pop_front();
-                    self.redraw(w)?;
-                    out
-                }
-                _ => {
-                    let out = self.tail.pop_front();
-                    self.print_tail(w)?;
-                    out
-                }
-            }
-            .ok_or(Error::EndOfInput)
-        }
-        pub fn len(&self) -> usize {
-            self.head.len() + self.tail.len()
-        }
-        pub fn is_empty(&self) -> bool {
-            self.head.is_empty() && self.tail.is_empty()
-        }
-        pub fn ends_with(&self, iter: impl DoubleEndedIterator<Item = char>) -> bool {
-            let mut iter = iter.rev();
-            let mut head = self.head.iter().rev();
-            loop {
-                match (iter.next(), head.next()) {
-                    (None, _) => break true,
-                    (Some(_), None) => break false,
-                    (Some(a), Some(b)) if a != *b => break false,
-                    (Some(_), Some(_)) => continue,
-                }
-            }
-        }
-        /// Moves the cursor back `steps` steps
-        pub fn cursor_back<W: Write>(&mut self, steps: usize, w: &mut W) -> ReplResult<()> {
-            for _ in 0..steps {
-                if let Some('\n') = self.head.back() {
-                    self.undraw(w)?;
-                }
-                let Some(c) = self.head.pop_back() else {
-                    return Ok(());
-                };
-                self.tail.push_front(c);
-                match c {
-                    '\n' => self.redraw(w)?,
-                    _ => queue!(w, MoveLeft(1))?,
-                }
-            }
-            Ok(())
-        }
-        /// Moves the cursor forward `steps` steps
-        pub fn cursor_forward<W: Write>(&mut self, steps: usize, w: &mut W) -> ReplResult<()> {
-            for _ in 0..steps {
-                if let Some('\n') = self.tail.front() {
-                    self.undraw(w)?
-                }
-                let Some(c) = self.tail.pop_front() else {
-                    return Ok(());
-                };
-                self.head.push_back(c);
-                match c {
-                    '\n' => self.redraw(w)?,
-                    _ => queue!(w, MoveRight(1))?,
-                }
-            }
-            Ok(())
-        }
-        /// Goes to the beginning of the current line
-        pub fn home<W: Write>(&mut self, w: &mut W) -> ReplResult<()> {
-            loop {
-                match self.head.back() {
-                    Some('\n') | None => break Ok(()),
-                    Some(_) => self.cursor_back(1, w)?,
-                }
-            }
-        }
-        /// Goes to the end of the current line
-        pub fn end<W: Write>(&mut self, w: &mut W) -> ReplResult<()> {
-            loop {
-                match self.tail.front() {
-                    Some('\n') | None => break Ok(()),
-                    Some(_) => self.cursor_forward(1, w)?,
-                }
-            }
-        }
-    }
-
-    impl<'a, 'e> IntoIterator for &'e Editor<'a> {
-        type Item = &'e char;
-        type IntoIter = std::iter::Chain<
-            std::collections::vec_deque::Iter<'e, char>,
-            std::collections::vec_deque::Iter<'e, char>,
-        >;
-        fn into_iter(self) -> Self::IntoIter {
-            self.head.iter().chain(self.tail.iter())
-        }
-    }
-    impl<'a> Display for Editor<'a> {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            use std::fmt::Write;
-            let Self { head, tail, .. } = self;
-            for c in head {
-                f.write_char(*c)?;
-            }
-            for c in tail {
-                f.write_char(*c)?;
-            }
-            Ok(())
-        }
-    }
-}

cl-structures/src/intern_pool.rs

@@ -1,131 +0,0 @@
-//! Trivially-copyable, easily comparable typed indices, and a [Pool] to contain them
-//!
-//! # Examples
-//!
-//! ```rust
-//! # use cl_structures::intern_pool::*;
-//! // first, create a new InternKey type (this ensures type safety)
-//! make_intern_key!{
-//!     NumbersKey
-//! }
-//!
-//! // then, create a pool with that type
-//! let mut numbers: Pool<i32, NumbersKey> = Pool::new();
-//! let first = numbers.insert(1);
-//! let second = numbers.insert(2);
-//! let third = numbers.insert(3);
-//!
-//! // You can access elements immutably with `get`
-//! assert_eq!(Some(&3), numbers.get(third));
-//! assert_eq!(Some(&2), numbers.get(second));
-//! // or by indexing
-//! assert_eq!(1, numbers[first]);
-//!
-//! // Or mutably
-//! *numbers.get_mut(first).unwrap() = 100000;
-//!
-//! assert_eq!(Some(&100000), numbers.get(first));
-//! ```
-
-/// Creates newtype indices over [`usize`] for use as [Pool] keys.
-#[macro_export]
-macro_rules! make_intern_key {($($(#[$meta:meta])* $name:ident),*$(,)?) => {$(
-    $(#[$meta])*
-    #[repr(transparent)]
-    #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
-    pub struct $name(usize);
-
-    impl $crate::intern_pool::InternKey for $name {
-        #[doc = concat!("Constructs a [`", stringify!($name), "`] from a [`usize`] without checking bounds.\n")]
-        /// # Safety
-        ///
-        /// The provided value should be within the bounds of its associated container
-        unsafe fn from_raw_unchecked(value: usize) -> Self {
-            Self(value)
-        }
-        fn get(&self) -> usize {
-            self.0
-        }
-    }
-    impl From< $name > for usize {
-        fn from(value: $name) -> Self {
-            value.0
-        }
-    }
-)*}}
-use std::ops::{Index, IndexMut};
-
-pub use make_intern_key;
-
-/// An index into a [Pool]. For full type-safety,
-/// there should be a unique [InternKey] for each [Pool]
-pub trait InternKey: std::fmt::Debug {
-    /// Constructs an [`InternKey`] from a [`usize`] without checking bounds.
-    ///
-    /// # Safety
-    ///
-    /// The provided value should be within the bounds of its associated container.
-    // ID::from_raw_unchecked here isn't *actually* unsafe, since bounds should always be
-    // checked, however, the function has unverifiable preconditions.
-    unsafe fn from_raw_unchecked(value: usize) -> Self;
-    /// Gets the index of the [`InternKey`] by value
-    fn get(&self) -> usize;
-}
-
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct Pool<T, ID: InternKey> {
-    pool: Vec<T>,
-    id_type: std::marker::PhantomData<ID>,
-}
-
-impl<T, ID: InternKey> Pool<T, ID> {
-    pub fn new() -> Self {
-        Self::default()
-    }
-    pub fn get(&self, index: ID) -> Option<&T> {
-        self.pool.get(index.get())
-    }
-    pub fn get_mut(&mut self, index: ID) -> Option<&mut T> {
-        self.pool.get_mut(index.get())
-    }
-
-    pub fn iter(&self) -> impl Iterator<Item = &T> {
-        self.pool.iter()
-    }
-    pub fn iter_mut(&mut self) -> impl Iterator<Item = &mut T> {
-        self.pool.iter_mut()
-    }
-
-    pub fn insert(&mut self, value: T) -> ID {
-        let id = self.pool.len();
-        self.pool.push(value);
-
-        // Safety: value was pushed to `self.pool[id]`
-        unsafe { ID::from_raw_unchecked(id) }
-    }
-}
-
-impl<T, ID: InternKey> Default for Pool<T, ID> {
-    fn default() -> Self {
-        Self { pool: vec![], id_type: std::marker::PhantomData }
-    }
-}
-
-impl<T, ID: InternKey> Index<ID> for Pool<T, ID> {
-    type Output = T;
-
-    fn index(&self, index: ID) -> &Self::Output {
-        match self.pool.get(index.get()) {
-            None => panic!("Index {:?} out of bounds in pool!", index),
-            Some(value) => value,
-        }
-    }
-}
-impl<T, ID: InternKey> IndexMut<ID> for Pool<T, ID> {
-    fn index_mut(&mut self, index: ID) -> &mut Self::Output {
-        match self.pool.get_mut(index.get()) {
-            None => panic!("Index {:?} out of bounds in pool!", index),
-            Some(value) => value,
-        }
-    }
-}

cl-structures/src/lib.rs

@@ -1,14 +0,0 @@
-//! # Universally useful structures
-//! - [Span](struct@span::Span): Stores a start and end [Loc](struct@span::Loc)
-//! - [Loc](struct@span::Loc): Stores the index in a stream
-#![warn(clippy::all)]
-#![feature(inline_const, dropck_eyepatch, decl_macro)]
-#![deny(unsafe_op_in_unsafe_fn)]
-
-pub mod span;
-
-pub mod tree;
-
-pub mod stack;
-
-pub mod intern_pool;

cl-typeck/src/lib.rs

@@ -1,909 +0,0 @@
-//! # The Conlang Type Checker
-//!
-//! As a statically typed language, Conlang requires a robust type checker to enforce correctness.
-#![feature(debug_closure_helpers)]
-#![warn(clippy::all)]
-
-/*
-
-The type checker keeps track of a *global intern pool* for Types and Values
-References to the intern pool are held by ID, and items cannot be freed from the pool EVER.
-
-Items are inserted into their respective pools,
-
-
-*/
-
-pub mod key {
-    use cl_structures::intern_pool::*;
-
-    // define the index types
-    make_intern_key! {
-        /// Uniquely represents a [Def][1] in the [Def][1] [Pool]
-        ///
-        /// [1]: crate::definition::Def
-        DefID,
-    }
-}
-
-pub mod definition {
-    use crate::{key::DefID, module::Module, type_kind::TypeKind, value_kind::ValueKind};
-    use cl_ast::{format::FmtPretty, Item, Meta, Visibility};
-    use std::fmt::Write;
-
-    #[derive(Clone, PartialEq, Eq)]
-    pub struct Def {
-        pub name: String,
-        pub vis: Visibility,
-        pub meta: Vec<Meta>,
-        pub kind: DefKind,
-        pub source: Option<Item>,
-        pub module: Module,
-    }
-
-    impl Default for Def {
-        fn default() -> Self {
-            Self {
-                name: Default::default(),
-                vis: Default::default(),
-                meta: Default::default(),
-                kind: DefKind::Type(TypeKind::Module),
-                source: Default::default(),
-                module: Default::default(),
-            }
-        }
-    }
-
-    impl Def {
-        pub fn new_module(
-            name: String,
-            vis: Visibility,
-            meta: Vec<Meta>,
-            parent: Option<DefID>,
-        ) -> Self {
-            Self {
-                name,
-                vis,
-                meta,
-                kind: DefKind::Type(TypeKind::Module),
-                source: None,
-                module: Module { parent, ..Default::default() },
-            }
-        }
-    }
-
-    impl std::fmt::Debug for Def {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            let Self { name, vis, meta, kind, source, module } = self;
-            f.debug_struct("Def")
-                .field("name", &name)
-                .field("vis", &vis)
-                .field_with("meta", |f| write!(f, "{meta:?}"))
-                .field("kind", &kind)
-                .field_with("source", |f| match source {
-                    Some(item) => write!(f.pretty(), "{{\n{item}\n}}"),
-                    None => todo!(),
-                })
-                .field("module", &module)
-                .finish()
-        }
-    }
-
-    #[derive(Clone, Debug, PartialEq, Eq)]
-    pub enum DefKind {
-        /// A type, such as a ``
-        Type(TypeKind),
-        /// A value, such as a `const`, `static`, or `fn`
-        Value(ValueKind),
-    }
-
-    impl DefKind {
-        pub fn is_type(&self) -> bool {
-            matches!(self, Self::Type(_))
-        }
-        pub fn ty(&self) -> Option<&TypeKind> {
-            match self {
-                DefKind::Type(t) => Some(t),
-                _ => None,
-            }
-        }
-        pub fn is_value(&self) -> bool {
-            matches!(self, Self::Value(_))
-        }
-        pub fn value(&self) -> Option<&ValueKind> {
-            match self {
-                DefKind::Value(v) => Some(v),
-                _ => None,
-            }
-        }
-    }
-}
-
-pub mod type_kind {
-    //! A [TypeKind] represents an item in the Type Namespace
-    //! (a component of a [Project](crate::project::Project)).
-
-    use cl_ast::Visibility;
-    use std::{fmt::Debug, str::FromStr};
-
-    use crate::key::DefID;
-
-    /// The kind of a type
-    #[derive(Clone, Debug, PartialEq, Eq)]
-    pub enum TypeKind {
-        /// A type which has not yet been resolved
-        Undecided,
-        /// An alias for an already-defined type
-        Alias(Option<DefID>),
-        /// A primitive type, built-in to the compiler
-        Intrinsic(Intrinsic),
-        /// A user-defined abstract data type
-        Adt(Adt),
-        /// A reference to an already-defined type: &T
-        Ref(DefID),
-        /// A contiguous view of dynamically sized memory
-        Slice(DefID),
-        /// A function pointer which accepts multiple inputs and produces an output
-        FnPtr { args: Vec<DefID>, rety: DefID },
-        /// The unit type
-        Empty,
-        /// The never type
-        Never,
-        /// The Self type
-        SelfTy,
-        /// An untyped module
-        Module,
-    }
-
-    /// A user-defined Abstract Data Type
-    #[derive(Clone, Debug, PartialEq, Eq)]
-    pub enum Adt {
-        /// A union-like enum type
-        Enum(Vec<(String, DefID)>),
-        CLikeEnum(Vec<(String, u128)>),
-        /// An enum with no fields, which can never be constructed
-        FieldlessEnum,
-
-        /// A structural product type with named members
-        Struct(Vec<(String, Visibility, DefID)>),
-        /// A structural product type with unnamed members
-        TupleStruct(Vec<(Visibility, DefID)>),
-        /// A structural product type of neither named nor unnamed members
-        UnitStruct,
-
-        /// A choose your own undefined behavior type
-        /// TODO: should unions be a language feature?
-        Union(Vec<(String, DefID)>),
-    }
-
-    /// The set of compiler-intrinsic types.
-    /// These primitive types have native implementations of the basic operations.
-    #[allow(non_camel_case_types)]
-    #[derive(Clone, Debug, PartialEq, Eq)]
-    pub enum Intrinsic {
-        /// An 8-bit signed integer: `#[intrinsic = "i8"]`
-        I8,
-        /// A 16-bit signed integer: `#[intrinsic = "i16"]`
-        I16,
-        /// A 32-bit signed integer: `#[intrinsic = "i32"]`
-        I32,
-        /// A 64-bit signed integer: `#[intrinsic = "i32"]`
-        I64,
-        // /// A 128-bit signed integer: `#[intrinsic = "i32"]`
-        // I128,
-        /// An 8-bit unsigned integer: `#[intrinsic = "u8"]`
-        U8,
-        /// A 16-bit unsigned integer: `#[intrinsic = "u16"]`
-        U16,
-        /// A 32-bit unsigned integer: `#[intrinsic = "u32"]`
-        U32,
-        /// A 64-bit unsigned integer: `#[intrinsic = "u64"]`
-        U64,
-        // /// A 128-bit unsigned integer: `#[intrinsic = "u128"]`
-        // U128,
-        /// A boolean (`true` or `false`): `#[intrinsic = "bool"]`
-        Bool,
-    }
-
-    impl FromStr for Intrinsic {
-        type Err = ();
-
-        fn from_str(s: &str) -> Result<Self, Self::Err> {
-            Ok(match s {
-                "i8" => Intrinsic::I8,
-                "i16" => Intrinsic::I16,
-                "i32" => Intrinsic::I32,
-                "i64" => Intrinsic::I64,
-                "u8" => Intrinsic::U8,
-                "u16" => Intrinsic::U16,
-                "u32" => Intrinsic::U32,
-                "u64" => Intrinsic::U64,
-                "bool" => Intrinsic::Bool,
-                _ => Err(())?,
-            })
-        }
-    }
-
-    #[derive(Clone, Debug, PartialEq, Eq)]
-    pub enum Float {
-        F32 = 0x20,
-        F64,
-    }
-}
-
-pub mod value_kind {
-    //! A [ValueKind] represents an item in the Value Namespace
-    //! (a component of a [Project](crate::project::Project)).
-
-    use crate::typeref::TypeRef;
-    use cl_ast::Block;
-
-    #[derive(Clone, Debug, PartialEq, Eq)]
-    pub enum ValueKind {
-        Undecided,
-        Const(TypeRef),
-        Static(TypeRef),
-        Fn {
-            // TODO: Store the variable bindings here!
-            args: Vec<TypeRef>,
-            rety: TypeRef,
-            body: Block,
-        },
-    }
-}
-
-pub mod module {
-    //! A [Module] is a node in the Module Tree (a component of a
-    //! [Project](crate::project::Project))
-    use crate::key::DefID;
-    use std::collections::HashMap;
-
-    /// A [Module] is a node in the Module Tree (a component of a
-    /// [Project](crate::project::Project)).
-    #[derive(Clone, Debug, Default, PartialEq, Eq)]
-    pub struct Module {
-        pub parent: Option<DefID>,
-        pub types: HashMap<String, DefID>,
-        pub values: HashMap<String, DefID>,
-    }
-
-    impl Module {
-        pub fn new(parent: DefID) -> Self {
-            Self { parent: Some(parent), ..Default::default() }
-        }
-    }
-}
-
-pub mod path {
-    use cl_ast::{Path as AstPath, PathPart};
-
-    #[derive(Clone, Copy, Debug, PartialEq, Eq)]
-    pub struct Path<'p> {
-        pub absolute: bool,
-        pub parts: &'p [PathPart],
-    }
-
-    impl<'p> Path<'p> {
-        pub fn new(path: &'p AstPath) -> Self {
-            let AstPath { absolute, parts } = path;
-            Self { absolute: *absolute, parts }
-        }
-        pub fn relative(self) -> Self {
-            Self { absolute: false, ..self }
-        }
-        pub fn pop_front(self) -> Option<Self> {
-            let Self { absolute, parts } = self;
-            Some(Self { absolute, parts: parts.get(1..)? })
-        }
-        pub fn is_empty(&self) -> bool {
-            self.parts.is_empty()
-        }
-        pub fn len(&self) -> usize {
-            self.parts.len()
-        }
-        pub fn front(&self) -> Option<&PathPart> {
-            self.parts.first()
-        }
-    }
-
-    impl<'p> From<&'p AstPath> for Path<'p> {
-        fn from(value: &'p AstPath) -> Self {
-            Self::new(value)
-        }
-    }
-    impl std::fmt::Display for Path<'_> {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            const SEPARATOR: &str = "::";
-            let Self { absolute, parts } = self;
-            if *absolute {
-                write!(f, "{SEPARATOR}")?
-            }
-            for (idx, part) in parts.iter().enumerate() {
-                write!(f, "{}{part}", if idx > 0 { SEPARATOR } else { "" })?;
-            }
-            Ok(())
-        }
-    }
-}
-
-pub mod project {
-    use crate::{
-        definition::{Def, DefKind},
-        key::DefID,
-        path::Path,
-        type_kind::TypeKind,
-    };
-    use cl_ast::{Identifier, PathPart, Visibility};
-    use cl_structures::intern_pool::Pool;
-    use std::ops::{Index, IndexMut};
-
-    #[derive(Clone, Debug, PartialEq, Eq)]
-    pub struct Project {
-        pub pool: Pool<Def, DefID>,
-        pub module_root: DefID,
-    }
-
-    impl Project {
-        pub fn new() -> Self {
-            Self::default()
-        }
-    }
-    impl Default for Project {
-        fn default() -> Self {
-            let mut pool = Pool::default();
-            let module_root = pool.insert(Def::default());
-            // Insert the Never(!) type
-            let never = pool.insert(Def {
-                name: String::from("!"),
-                vis: Visibility::Public,
-                kind: DefKind::Type(TypeKind::Never),
-                ..Default::default()
-            });
-            pool[module_root]
-                .module
-                .types
-                .insert(String::from("!"), never);
-            Self { pool, module_root }
-        }
-    }
-
-    impl Project {
-        pub fn parent_of(&self, module: DefID) -> Option<DefID> {
-            self[module].module.parent
-        }
-        pub fn root_of(&self, module: DefID) -> DefID {
-            match self.parent_of(module) {
-                Some(module) => self.root_of(module),
-                None => module,
-            }
-        }
-        /// Resolves a path within a module tree, finding the innermost module.
-        /// Returns the remaining path parts.
-        pub fn get_type<'a>(&self, path: Path<'a>, within: DefID) -> Option<(DefID, Path<'a>)> {
-            // TODO: Cache module lookups
-            if path.absolute {
-                self.get_type(path.relative(), self.root_of(within))
-            } else if let Some(front) = path.front() {
-                let module = &self[within].module;
-                match front {
-                    PathPart::SelfKw => self.get_type(path.pop_front()?, within),
-                    PathPart::SuperKw => self.get_type(path.pop_front()?, module.parent?),
-                    PathPart::Ident(Identifier(name)) => match module.types.get(name) {
-                        Some(&submodule) => self.get_type(path.pop_front()?, submodule),
-                        None => Some((within, path)),
-                    },
-                }
-            } else {
-                Some((within, path))
-            }
-        }
-
-        pub fn get_value<'a>(&self, path: Path<'a>, within: DefID) -> Option<(DefID, Path<'a>)> {
-            match path.front()? {
-                PathPart::Ident(Identifier(name)) => Some((
-                    self[within].module.values.get(name).copied()?,
-                    path.pop_front()?,
-                )),
-                _ => None,
-            }
-        }
-
-        #[rustfmt::skip]
-        pub fn insert_type(&mut self, name: String, value: Def, parent: DefID) -> Option<DefID> {
-            let id = self.pool.insert(value);
-            self[parent].module.types.insert(name, id)
-        }
-        #[rustfmt::skip]
-        pub fn insert_value(&mut self, name: String, value: Def, parent: DefID) -> Option<DefID> {
-            let id = self.pool.insert(value);
-            self[parent].module.values.insert(name, id)
-        }
-    }
-
-    /// Implements [Index] and [IndexMut] for [Project]: `self.table[ID] -> Definition`
-    macro_rules! impl_index {
-        ($(self.$table:ident[$idx:ty] -> $out:ty),*$(,)?) => {$(
-            impl Index<$idx> for Project {
-                type Output = $out;
-                fn index(&self, index: $idx) -> &Self::Output {
-                    &self.$table[index]
-                }
-            }
-            impl IndexMut<$idx> for Project {
-                fn index_mut(&mut self, index: $idx) -> &mut Self::Output {
-                    &mut self.$table[index]
-                }
-            }
-        )*};
-    }
-    impl_index! {
-        self.pool[DefID] -> Def,
-        // self.types[TypeID] -> TypeDef,
-        // self.values[ValueID] -> ValueDef,
-    }
-}
-
-pub mod name_collector {
-    //! Performs step 1 of type checking: Collecting all the names of things into [Module] units
-
-    use crate::{
-        definition::{Def, DefKind},
-        key,
-        project::Project,
-        type_kind::{Adt, TypeKind},
-        value_kind::ValueKind,
-    };
-    use cl_ast::*;
-    use std::ops::{Deref, DerefMut};
-
-    /// Collects types for future use
-    #[derive(Debug, PartialEq, Eq)]
-    pub struct NameCollector<'prj> {
-        /// A stack of the current modules
-        pub mod_stack: Vec<key::DefID>,
-        /// The [Project], the type checker and resolver's central data store
-        pub project: &'prj mut Project,
-    }
-
-    impl<'prj> NameCollector<'prj> {
-        pub fn new(project: &'prj mut Project) -> Self {
-            // create a root module
-            Self { mod_stack: vec![project.module_root], project }
-        }
-
-        /// Gets the currently traversed parent module
-        pub fn parent(&self) -> Option<key::DefID> {
-            self.mod_stack.last().copied()
-        }
-    }
-
-    impl Deref for NameCollector<'_> {
-        type Target = Project;
-        fn deref(&self) -> &Self::Target {
-            self.project
-        }
-    }
-    impl DerefMut for NameCollector<'_> {
-        fn deref_mut(&mut self) -> &mut Self::Target {
-            self.project
-        }
-    }
-
-    impl NameCollector<'_> {
-        pub fn file(&mut self, f: &File) -> Result<(), &'static str> {
-            let parent = self.parent().ok_or("No parent to add item to")?;
-
-            for item in &f.items {
-                let def = match &item.kind {
-                    // modules
-                    // types
-                    ItemKind::Module(_) => {
-                        self.module(item)?;
-                        continue;
-                    }
-                    ItemKind::Enum(_) => Some(self.ty_enum(item)?),
-                    ItemKind::Alias(_) => Some(self.ty_alias(item)?),
-                    ItemKind::Struct(_) => Some(self.ty_struct(item)?),
-                    // values processed by the value collector
-                    ItemKind::Const(_) => Some(self.val_const(item)?),
-                    ItemKind::Static(_) => Some(self.val_static(item)?),
-                    ItemKind::Function(_) => Some(self.val_function(item)?),
-                    ItemKind::Impl(_) => None,
-                };
-                let Some(def) = def else { continue };
-                match def.kind {
-                    DefKind::Type(_) => {
-                        if let Some(v) = self.insert_type(def.name.clone(), def, parent) {
-                            panic!("Redefinition of type {} ({v:?})!", self[v].name)
-                        }
-                    }
-                    DefKind::Value(_) => {
-                        if let Some(v) = self.insert_value(def.name.clone(), def, parent) {
-                            panic!("Redefinition of value {} ({v:?})!", self[v].name)
-                        }
-                    }
-                }
-            }
-            Ok(())
-        }
-
-        /// Collects a [Module]
-        pub fn module(&mut self, m: &Item) -> Result<(), &'static str> {
-            let Item { kind: ItemKind::Module(Module { name, kind }), vis, attrs, .. } = m else {
-                Err("module called on Item which was not an ItemKind::Module")?
-            };
-            let ModuleKind::Inline(kind) = kind else {
-                Err("Out-of-line modules not yet supported")?
-            };
-            let parent = self.parent().ok_or("No parent to add module to")?;
-
-            let module = self.pool.insert(Def::new_module(
-                name.0.clone(),
-                *vis,
-                attrs.meta.clone(),
-                Some(parent),
-            ));
-
-            self[parent]
-                .module
-                .types
-                .insert(name.0.clone(), module)
-                .is_some()
-                .then(|| panic!("Error: redefinition of module {name}"));
-
-            self.mod_stack.push(module);
-            let out = self.file(kind);
-            self.mod_stack.pop();
-
-            out
-        }
-    }
-    /// Type collection
-    impl NameCollector<'_> {
-        /// Collects an [Item] of type [ItemKind::Enum]
-        pub fn ty_enum(&mut self, item: &Item) -> Result<Def, &'static str> {
-            let Item { kind: ItemKind::Enum(Enum { name, kind }), vis, attrs, .. } = item else {
-                Err("Enum called on item which was not ItemKind::Enum")?
-            };
-            let kind = match kind {
-                EnumKind::NoVariants => DefKind::Type(TypeKind::Adt(Adt::FieldlessEnum)),
-                EnumKind::Variants(_) => DefKind::Type(TypeKind::Undecided),
-            };
-
-            Ok(Def {
-                name: name.0.clone(),
-                vis: *vis,
-                meta: attrs.meta.clone(),
-                kind,
-                source: Some(item.clone()),
-                module: Default::default(),
-            })
-        }
-
-        /// Collects an [Item] of type [ItemKind::Alias]
-        pub fn ty_alias(&mut self, item: &Item) -> Result<Def, &'static str> {
-            let Item { kind: ItemKind::Alias(Alias { to: name, from }), vis, attrs, .. } = item
-            else {
-                Err("Alias called on Item which was not ItemKind::Alias")?
-            };
-
-            let mut kind = match from {
-                Some(_) => DefKind::Type(TypeKind::Undecided),
-                None => DefKind::Type(TypeKind::Alias(None)),
-            };
-
-            for meta in &attrs.meta {
-                let Meta { name: meta_name, kind: meta_kind } = meta;
-                match (meta_name.0.as_str(), meta_kind) {
-                    ("intrinsic", MetaKind::Equals(Literal::String(intrinsic))) => {
-                        kind = DefKind::Type(TypeKind::Intrinsic(
-                            intrinsic.parse().map_err(|_| "unknown intrinsic type")?,
-                        ));
-                    }
-                    ("intrinsic", MetaKind::Plain) => {
-                        kind = DefKind::Type(TypeKind::Intrinsic(
-                            name.0.parse().map_err(|_| "Unknown intrinsic type")?,
-                        ))
-                    }
-                    _ => {}
-                }
-            }
-
-            Ok(Def {
-                name: name.0.clone(),
-                vis: *vis,
-                meta: attrs.meta.clone(),
-                kind,
-                source: Some(item.clone()),
-                module: Default::default(),
-            })
-        }
-
-        /// Collects an [Item] of type [ItemKind::Struct]
-        pub fn ty_struct(&mut self, item: &Item) -> Result<Def, &'static str> {
-            let Item { kind: ItemKind::Struct(Struct { name, kind }), vis, attrs, .. } = item
-            else {
-                Err("Struct called on item which was not ItemKind::Struct")?
-            };
-            let kind = match kind {
-                StructKind::Empty => DefKind::Type(TypeKind::Adt(Adt::UnitStruct)),
-                StructKind::Tuple(_) => DefKind::Type(TypeKind::Undecided),
-                StructKind::Struct(_) => DefKind::Type(TypeKind::Undecided),
-            };
-
-            Ok(Def {
-                name: name.0.clone(),
-                vis: *vis,
-                meta: attrs.meta.clone(),
-                kind,
-                source: Some(item.clone()),
-                module: Default::default(),
-            })
-        }
-    }
-    /// Value collection
-    impl NameCollector<'_> {
-        pub fn val_const(&mut self, item: &Item) -> Result<Def, &'static str> {
-            let Item { kind: ItemKind::Const(Const { name, .. }), vis, attrs, .. } = item else {
-                Err("Const called on Item which was not ItemKind::Const")?
-            };
-
-            Ok(Def {
-                name: name.0.clone(),
-                vis: *vis,
-                meta: attrs.meta.clone(),
-                kind: DefKind::Value(ValueKind::Undecided),
-                source: Some(item.clone()),
-                module: Default::default(),
-            })
-        }
-
-        pub fn val_static(&mut self, item: &Item) -> Result<Def, &'static str> {
-            let Item { kind: ItemKind::Static(Static { name, .. }), vis, attrs, .. } = item else {
-                Err("Static called on Item which was not ItemKind::Static")?
-            };
-            Ok(Def {
-                name: name.0.clone(),
-                vis: *vis,
-                meta: attrs.meta.clone(),
-                kind: DefKind::Type(TypeKind::Undecided),
-                source: Some(item.clone()),
-                module: Default::default(),
-            })
-        }
-
-        pub fn val_function(&mut self, item: &Item) -> Result<Def, &'static str> {
-            // TODO: treat function bodies like modules with internal items
-            let Item { kind: ItemKind::Function(Function { name, .. }), vis, attrs, .. } = item
-            else {
-                Err("val_function called on Item which was not ItemKind::Function")?
-            };
-            Ok(Def {
-                name: name.0.clone(),
-                vis: *vis,
-                meta: attrs.meta.clone(),
-                kind: DefKind::Value(ValueKind::Undecided),
-                source: Some(item.clone()),
-                module: Default::default(),
-            })
-        }
-    }
-}
-
-pub mod type_resolver {
-    //! Performs step 2 of type checking: Evaluating type definitions
-    #![allow(unused)]
-    use std::ops::{Deref, DerefMut};
-
-    use cl_ast::*;
-
-    use crate::{definition::Def, key::DefID, project::Project};
-
-    pub struct TypeResolver<'prj> {
-        pub project: &'prj mut Project,
-    }
-
-    impl Deref for TypeResolver<'_> {
-        type Target = Project;
-        fn deref(&self) -> &Self::Target {
-            self.project
-        }
-    }
-    impl DerefMut for TypeResolver<'_> {
-        fn deref_mut(&mut self) -> &mut Self::Target {
-            self.project
-        }
-    }
-
-    impl TypeResolver<'_> {
-        pub fn resolve(&mut self) -> Result<bool, &str> {
-            #![allow(unused)]
-            for typedef in self.pool.iter_mut().filter(|v| v.kind.is_type()) {
-                let Def { name, vis, meta: attr, kind, source: Some(ref definition), module: _ } =
-                    typedef
-                else {
-                    continue;
-                };
-                match &definition.kind {
-                    ItemKind::Alias(Alias { to: _, from: Some(from) }) => match &from.kind {
-                        TyKind::Never => todo!(),
-                        TyKind::Empty => todo!(),
-                        TyKind::SelfTy => todo!(),
-                        TyKind::Path(_) => todo!(),
-                        TyKind::Tuple(_) => todo!(),
-                        TyKind::Ref(_) => todo!(),
-                        TyKind::Fn(_) => todo!(),
-                    },
-                    ItemKind::Alias(_) => {}
-                    ItemKind::Const(_) => todo!(),
-                    ItemKind::Static(_) => todo!(),
-                    ItemKind::Module(_) => todo!(),
-                    ItemKind::Function(_) => {}
-                    ItemKind::Struct(_) => {}
-                    ItemKind::Enum(_) => {}
-                    ItemKind::Impl(_) => {}
-                }
-            }
-            Ok(true)
-        }
-
-        pub fn get_type(&self, kind: &TyKind) -> Option<DefID> {
-            match kind {
-                TyKind::Never => todo!(),
-                TyKind::Empty => todo!(),
-                TyKind::SelfTy => todo!(),
-                TyKind::Path(_) => todo!(),
-                TyKind::Tuple(_) => todo!(),
-                TyKind::Ref(_) => todo!(),
-                TyKind::Fn(_) => todo!(),
-            }
-            None
-        }
-    }
-}
-
-pub mod typeref {
-    //! Stores type and reference info
-
-    use crate::key::DefID;
-
-    /// The Type struct represents all valid types, and can be trivially equality-compared
-    #[derive(Clone, Debug, PartialEq, Eq)]
-    pub struct TypeRef {
-        /// You can only have a pointer chain 65535 pointers long.
-        ref_depth: u16,
-        /// Types can be [Generic](RefKind::Generic) or [Concrete](RefKind::Concrete)
-        kind: RefKind,
-    }
-
-    /// Types can be [Generic](RefKind::Generic) or [Concrete](RefKind::Concrete)
-    #[derive(Clone, Debug, PartialEq, Eq)]
-    pub enum RefKind {
-        /// A Concrete type has an associated [Def](super::definition::Def)
-        Concrete(DefID),
-        /// A Generic type is a *locally unique* comparable value,
-        /// valid only until the end of its typing context.
-        /// This is usually the surrounding function.
-        Generic(usize),
-    }
-}
-
-/*
-/// What is an inference rule?
-/// An inference rule is a specification with a set of predicates and a judgement
-
-/// Let's give every type an ID
-struct TypeID(usize);
-
-/// Let's give every type some data:
-
-struct TypeDef<'def> {
-    name: String,
-    definition: &'def Item,
-}
-
-and store them in a big vector of type descriptions:
-
-struct TypeMap<'def> {
-    types: Vec<TypeDef<'def>>,
-}
-// todo: insertion of a type should yield a TypeID
-// todo: impl index with TypeID
-
-Let's store type information as either a concrete type or a generic type:
-
-/// The Type struct represents all valid types, and can be trivially equality-compared
-pub struct Type {
-    /// You can only have a pointer chain 65535 pointers long.
-    ref_depth: u16,
-    kind: TKind,
-}
-pub enum TKind {
-    Concrete(TypeID),
-    Generic(usize),
-}
-
-And assume I can specify a rule based on its inputs and outputs:
-
-Rule {
-    operation: If,
-    /// The inputs field is populated by
-    inputs: [Concrete(BOOL), Generic(0), Generic(0)],
-    outputs: Generic(0),
-    /// This rule is compiler-intrinsic!
-    through: None,
-}
-
-Rule {
-    operation: Add,
-    inputs: [Concrete(I32), Concrete(I32)],
-    outputs: Concrete(I32),
-    /// This rule is not compiler-intrinsic (it is overloaded!)
-    through: Some(&ImplAddForI32::Add),
-}
-
-
-
-These rules can be stored in some kind of rule database:
-
-let rules: Hashmap<Operation, Vec<Rule>> {
-
-}
-
-*/
-
-pub mod rule {
-    use crate::{key::DefID, typeref::TypeRef};
-
-    pub struct Rule {
-        /// What is this Rule for?
-        pub operation: (),
-        /// What inputs does it take?
-        pub inputs: Vec<TypeRef>,
-        /// What output does it produce?
-        pub output: TypeRef,
-        /// Where did this rule come from?
-        pub through: Origin,
-    }
-
-    // TODO: Genericize
-    pub enum Operation {
-        Mul,
-        Div,
-        Rem,
-        Add,
-        Sub,
-
-        Deref,
-        Neg,
-        Not,
-        At,
-        Tilde,
-
-        Index,
-
-        If,
-        While,
-        For,
-    }
-
-    pub enum Origin {
-        /// This rule is built into the compiler
-        Intrinsic,
-        /// This rule is derived from an implementation on a type
-        Extrinsic(DefID),
-    }
-}
-
-pub mod typeck {
-    #![allow(unused)]
-    use cl_ast::*;
-
-    pub struct Context {
-        rules: (),
-    }
-
-    trait TypeCheck {}
-}
-
-//

compiler/cl-ast/src/ast.rs

@@ -0,0 +1,650 @@
+//! # The Abstract Syntax Tree
+//! Contains definitions of Conlang AST Nodes.
+//!
+//! # Notable nodes
+//! - [Item] and [ItemKind]: Top-level constructs
+//! - [Stmt] and [StmtKind]: Statements
+//! - [Expr] and [ExprKind]: Expressions
+//!   - [Assign], [Modify], [Binary], and [Unary] expressions
+//!   - [ModifyKind], [BinaryKind], and [UnaryKind] operators
+//! - [Ty] and [TyKind]: Type qualifiers
+//! - [Pattern]: Pattern matching operators
+//! - [Path]: Path expressions
+use cl_structures::{intern::interned::Interned, span::*};
+
+/// An [Interned] static [str], used in place of an identifier
+pub type Sym = Interned<'static, str>;
+
+/// Whether a binding ([Static] or [Let]) or reference is mutable or not
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Hash)]
+pub enum Mutability {
+    #[default]
+    Not,
+    Mut,
+}
+
+/// Whether an [Item] is visible outside of the current [Module]
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Hash)]
+pub enum Visibility {
+    #[default]
+    Private,
+    Public,
+}
+
+/// A list of [Item]s
+#[derive(Clone, Debug, Default, PartialEq, Eq, Hash)]
+pub struct File {
+    pub name: &'static str,
+    pub items: Vec<Item>,
+}
+
+/// A list of [Meta] decorators
+#[derive(Clone, Debug, Default, PartialEq, Eq, Hash)]
+pub struct Attrs {
+    pub meta: Vec<Meta>,
+}
+
+/// A metadata decorator
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Meta {
+    pub name: Sym,
+    pub kind: MetaKind,
+}
+
+/// Information attached to [Meta]data
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub enum MetaKind {
+    Plain,
+    Equals(Literal),
+    Func(Vec<Literal>),
+}
+
+// Items
+/// Anything that can appear at the top level of a [File]
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Item {
+    pub span: Span,
+    pub attrs: Attrs,
+    pub vis: Visibility,
+    pub kind: ItemKind,
+}
+
+/// What kind of [Item] is this?
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub enum ItemKind {
+    // TODO: Trait declaration ("trait") item?
+    /// A [module](Module)
+    Module(Module),
+    /// A [type alias](Alias)
+    Alias(Alias),
+    /// An [enumerated type](Enum), with a discriminant and optional data
+    Enum(Enum),
+    /// A [structure](Struct)
+    Struct(Struct),
+    /// A [constant](Const)
+    Const(Const),
+    /// A [static](Static) variable
+    Static(Static),
+    /// A [function definition](Function)
+    Function(Function),
+    /// An [implementation](Impl)
+    Impl(Impl),
+    /// An [import](Use)
+    Use(Use),
+}
+
+/// A list of type variables to introduce
+#[derive(Clone, Debug, Default, PartialEq, Eq, Hash)]
+pub struct Generics {
+    pub vars: Vec<Sym>,
+}
+
+/// An ordered collection of [Items](Item)
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Module {
+    pub name: Sym,
+    pub file: Option<File>,
+}
+
+/// An alias to another [Ty]
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Alias {
+    pub name: Sym,
+    pub from: Option<Box<Ty>>,
+}
+
+/// A compile-time constant
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Const {
+    pub name: Sym,
+    pub ty: Box<Ty>,
+    pub init: Box<Expr>,
+}
+
+/// A `static` variable
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Static {
+    pub mutable: Mutability,
+    pub name: Sym,
+    pub ty: Box<Ty>,
+    pub init: Box<Expr>,
+}
+
+/// Code, and the interface to that code
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Function {
+    pub name: Sym,
+    pub gens: Generics,
+    pub sign: TyFn,
+    pub bind: Pattern,
+    pub body: Option<Expr>,
+}
+
+/// A user-defined product type
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Struct {
+    pub name: Sym,
+    pub gens: Generics,
+    pub kind: StructKind,
+}
+
+/// Either a [Struct]'s [StructMember]s or tuple [Ty]pes, if present.
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub enum StructKind {
+    Empty,
+    Tuple(Vec<Ty>),
+    Struct(Vec<StructMember>),
+}
+
+/// The [Visibility], [Sym], and [Ty]pe of a single [Struct] member
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct StructMember {
+    pub vis: Visibility,
+    pub name: Sym,
+    pub ty: Ty,
+}
+
+/// A user-defined sum type
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Enum {
+    pub name: Sym,
+    pub gens: Generics,
+    pub variants: Vec<Variant>,
+}
+
+/// A single [Enum] variant
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Variant {
+    pub name: Sym,
+    pub kind: StructKind,
+    pub body: Option<Box<Expr>>,
+}
+
+/// Sub-[items](Item) (associated functions, etc.) for a [Ty]
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Impl {
+    pub gens: Generics,
+    pub target: ImplKind,
+    pub body: File,
+}
+
+// TODO: `impl` Trait for <Target> { }
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub enum ImplKind {
+    Type(Ty),
+    Trait { impl_trait: Path, for_type: Box<Ty> },
+}
+
+/// An import of nonlocal [Item]s
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Use {
+    pub absolute: bool,
+    pub tree: UseTree,
+}
+
+/// A tree of [Item] imports
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub enum UseTree {
+    Tree(Vec<UseTree>),
+    Path(PathPart, Box<UseTree>),
+    Alias(Sym, Sym),
+    Name(Sym),
+    Glob,
+}
+
+/// A type expression
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Ty {
+    pub span: Span,
+    pub kind: TyKind,
+    pub gens: Generics,
+}
+
+/// Information about a [Ty]pe expression
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub enum TyKind {
+    Never,
+    Infer,
+    Path(Path),
+    Array(TyArray),
+    Slice(TySlice),
+    Tuple(TyTuple),
+    Ref(TyRef),
+    Ptr(TyPtr),
+    Fn(TyFn),
+}
+
+/// An array of [`T`](Ty)
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct TyArray {
+    pub ty: Box<Ty>,
+    pub count: usize,
+}
+
+/// A [Ty]pe slice expression: `[T]`
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct TySlice {
+    pub ty: Box<Ty>,
+}
+
+/// A tuple of [Ty]pes
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct TyTuple {
+    pub types: Vec<Ty>,
+}
+
+/// A [Ty]pe-reference expression as (number of `&`, [Path])
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct TyRef {
+    pub mutable: Mutability,
+    pub count: u16,
+    pub to: Box<Ty>,
+}
+
+/// A [Ty]pe-reference expression as (number of `&`, [Path])
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct TyPtr {
+    pub to: Box<Ty>,
+}
+
+/// The args and return value for a function pointer [Ty]pe
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct TyFn {
+    pub args: Box<Ty>,
+    pub rety: Box<Ty>,
+}
+
+/// A path to an [Item] in the [Module] tree
+#[derive(Clone, Debug, Default, PartialEq, Eq, Hash)]
+pub struct Path {
+    pub absolute: bool,
+    pub parts: Vec<PathPart>,
+}
+
+/// A single component of a [Path]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum PathPart {
+    SuperKw,
+    SelfTy,
+    Ident(Sym),
+}
+
+/// An abstract statement, and associated metadata
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Stmt {
+    pub span: Span,
+    pub kind: StmtKind,
+    pub semi: Semi,
+}
+
+/// Whether the [Stmt] is a [Let], [Item], or [Expr] statement
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub enum StmtKind {
+    Empty,
+    Item(Box<Item>),
+    Expr(Box<Expr>),
+}
+
+/// Whether or not a [Stmt] is followed by a semicolon
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub enum Semi {
+    Terminated,
+    Unterminated,
+}
+
+/// An expression, the beating heart of the language
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Expr {
+    pub span: Span,
+    pub kind: ExprKind,
+}
+
+/// Any of the different [Expr]essions
+#[derive(Clone, Default, Debug, PartialEq, Eq, Hash)]
+pub enum ExprKind {
+    /// An empty expression: `(` `)`
+    #[default]
+    Empty,
+    /// A [Closure] expression: `|` [`Expr`] `|` ( -> [`Ty`])? [`Expr`]
+    Closure(Closure),
+    /// A [Tuple] expression: `(` [`Expr`] (`,` [`Expr`])+ `)`
+    Tuple(Tuple),
+    /// A [Struct creation](Structor) expression: [Path] `{` ([Fielder] `,`)* [Fielder]? `}`
+    Structor(Structor),
+    /// An [Array] literal: `[` [`Expr`] (`,` [`Expr`])\* `]`
+    Array(Array),
+    /// An Array literal constructed with [repeat syntax](ArrayRep)
+    /// `[` [Expr] `;` [Literal] `]`
+    ArrayRep(ArrayRep),
+    /// An address-of expression: `&` `mut`? [`Expr`]
+    AddrOf(AddrOf),
+    /// A backtick-quoted expression
+    Quote(Quote),
+    /// A [Literal]: 0x42, 1e123, 2.4, "Hello"
+    Literal(Literal),
+    /// A [Grouping](Group) expression `(` [`Expr`] `)`
+    Group(Group),
+    /// A [Block] expression: `{` [`Stmt`]\* [`Expr`]? `}`
+    Block(Block),
+
+    /// An [Assign]ment expression: [`Expr`] (`=` [`Expr`])\+
+    Assign(Assign),
+    /// A [Modify]-assignment expression: [`Expr`] ([`ModifyKind`] [`Expr`])\+
+    Modify(Modify),
+    /// A [Binary] expression: [`Expr`] ([`BinaryKind`] [`Expr`])\+
+    Binary(Binary),
+    /// A [Unary] expression: [`UnaryKind`]\* [`Expr`]
+    Unary(Unary),
+    /// A [Member] access expression: [`Expr`] [`MemberKind`]\*
+    Member(Member),
+    /// An Array [Index] expression: a[10, 20, 30]
+    Index(Index),
+    /// A [Cast] expression: [`Expr`] `as` [`Ty`]
+    Cast(Cast),
+    /// A [path expression](Path): `::`? [PathPart] (`::` [PathPart])*
+    Path(Path),
+    /// A local bind instruction, `let` [`Sym`] `=` [`Expr`]
+    Let(Let),
+    /// A [Match] expression: `match` [Expr] `{` ([MatchArm] `,`)* [MatchArm]? `}`
+    Match(Match),
+    /// A [While] expression: `while` [`Expr`] [`Block`] [`Else`]?
+    While(While),
+    /// An [If] expression: `if` [`Expr`] [`Block`] [`Else`]?
+    If(If),
+    /// A [For] expression: `for` [`Pattern`] `in` [`Expr`] [`Block`] [`Else`]?
+    For(For),
+    /// A [Break] expression: `break` [`Expr`]?
+    Break(Break),
+    /// A [Return] expression `return` [`Expr`]?
+    Return(Return),
+    /// A continue expression: `continue`
+    Continue,
+}
+
+/// A Closure [expression](Expr): `|` [`Expr`] `|` ( -> [`Ty`])? [`Expr`]
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Closure {
+    pub arg: Box<Pattern>,
+    pub body: Box<Expr>,
+}
+
+/// A [Tuple] expression: `(` [`Expr`] (`,` [`Expr`])+ `)`
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Tuple {
+    pub exprs: Vec<Expr>,
+}
+
+/// A [Struct creation](Structor) expression: [Path] `{` ([Fielder] `,`)* [Fielder]? `}`
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Structor {
+    pub to: Path,
+    pub init: Vec<Fielder>,
+}
+
+/// A [Struct field initializer] expression: [Sym] (`=` [Expr])?
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Fielder {
+    pub name: Sym,
+    pub init: Option<Box<Expr>>,
+}
+
+/// An [Array] literal: `[` [`Expr`] (`,` [`Expr`])\* `]`
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Array {
+    pub values: Vec<Expr>,
+}
+
+/// An Array literal constructed with [repeat syntax](ArrayRep)
+/// `[` [Expr] `;` [Literal] `]`
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct ArrayRep {
+    pub value: Box<Expr>,
+    pub repeat: Box<Expr>,
+}
+
+/// An address-of expression: `&` `mut`? [`Expr`]
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct AddrOf {
+    pub mutable: Mutability,
+    pub expr: Box<Expr>,
+}
+
+/// A cast expression: [`Expr`] `as` [`Ty`]
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Cast {
+    pub head: Box<Expr>,
+    pub ty: Ty,
+}
+
+/// A backtick-quoted subexpression-literal
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Quote {
+    pub quote: Box<Expr>,
+}
+
+/// A [Literal]: 0x42, 1e123, 2.4, "Hello"
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub enum Literal {
+    Bool(bool),
+    Char(char),
+    Int(u128),
+    Float(u64),
+    String(String),
+}
+
+/// A [Grouping](Group) expression `(` [`Expr`] `)`
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Group {
+    pub expr: Box<Expr>,
+}
+
+/// A [Block] expression: `{` [`Stmt`]\* [`Expr`]? `}`
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Block {
+    pub stmts: Vec<Stmt>,
+}
+
+/// An [Assign]ment expression: [`Expr`] ([`ModifyKind`] [`Expr`])\+
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Assign {
+    pub parts: Box<(Expr, Expr)>,
+}
+
+/// A [Modify]-assignment expression: [`Expr`] ([`ModifyKind`] [`Expr`])\+
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Modify {
+    pub kind: ModifyKind,
+    pub parts: Box<(Expr, Expr)>,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum ModifyKind {
+    And,
+    Or,
+    Xor,
+    Shl,
+    Shr,
+    Add,
+    Sub,
+    Mul,
+    Div,
+    Rem,
+}
+
+/// A [Binary] expression: [`Expr`] ([`BinaryKind`] [`Expr`])\+
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Binary {
+    pub kind: BinaryKind,
+    pub parts: Box<(Expr, Expr)>,
+}
+
+/// A [Binary] operator
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum BinaryKind {
+    Lt,
+    LtEq,
+    Equal,
+    NotEq,
+    GtEq,
+    Gt,
+    RangeExc,
+    RangeInc,
+    LogAnd,
+    LogOr,
+    LogXor,
+    BitAnd,
+    BitOr,
+    BitXor,
+    Shl,
+    Shr,
+    Add,
+    Sub,
+    Mul,
+    Div,
+    Rem,
+    Call,
+}
+
+/// A [Unary] expression: [`UnaryKind`]\* [`Expr`]
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Unary {
+    pub kind: UnaryKind,
+    pub tail: Box<Expr>,
+}
+
+/// A [Unary] operator
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum UnaryKind {
+    Deref,
+    Neg,
+    Not,
+    RangeInc,
+    RangeExc,
+    /// A Loop expression: `loop` [`Block`]
+    Loop,
+    /// Unused
+    At,
+    /// Unused
+    Tilde,
+}
+
+/// A [Member] access expression: [`Expr`] [`MemberKind`]\*
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Member {
+    pub head: Box<Expr>,
+    pub kind: MemberKind,
+}
+
+/// The kind of [Member] access
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub enum MemberKind {
+    Call(Sym, Tuple),
+    Struct(Sym),
+    Tuple(Literal),
+}
+
+/// A repeated [Index] expression: a[10, 20, 30][40, 50, 60]
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Index {
+    pub head: Box<Expr>,
+    pub indices: Vec<Expr>,
+}
+
+/// A local variable declaration [Stmt]
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Let {
+    pub mutable: Mutability,
+    pub name: Pattern,
+    pub ty: Option<Box<Ty>>,
+    pub init: Option<Box<Expr>>,
+}
+
+/// A `match` expression: `match` `{` ([MatchArm] `,`)* [MatchArm]? `}`
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Match {
+    pub scrutinee: Box<Expr>,
+    pub arms: Vec<MatchArm>,
+}
+
+/// A single arm of a [Match] expression: [`Pattern`] `=>` [`Expr`]
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct MatchArm(pub Pattern, pub Expr);
+
+/// A [Pattern] meta-expression (any [`ExprKind`] that fits pattern rules)
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub enum Pattern {
+    Name(Sym),
+    Path(Path),
+    Literal(Literal),
+    Rest(Option<Box<Pattern>>),
+    Ref(Mutability, Box<Pattern>),
+    RangeExc(Box<Pattern>, Box<Pattern>),
+    RangeInc(Box<Pattern>, Box<Pattern>),
+    Tuple(Vec<Pattern>),
+    Array(Vec<Pattern>),
+    Struct(Path, Vec<(Sym, Option<Pattern>)>),
+    TupleStruct(Path, Vec<Pattern>),
+}
+
+/// A [While] expression: `while` [`Expr`] [`Block`] [`Else`]?
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct While {
+    pub cond: Box<Expr>,
+    pub pass: Box<Block>,
+    pub fail: Else,
+}
+
+/// An [If] expression: `if` [`Expr`] [`Block`] [`Else`]?
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct If {
+    pub cond: Box<Expr>,
+    pub pass: Box<Block>,
+    pub fail: Else,
+}
+
+/// A [For] expression: `for` Pattern `in` [`Expr`] [`Block`] [`Else`]?
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct For {
+    pub bind: Pattern,
+    pub cond: Box<Expr>,
+    pub pass: Box<Block>,
+    pub fail: Else,
+}
+
+/// The (optional) `else` clause of a [While], [If], or [For] expression
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Else {
+    pub body: Option<Box<Expr>>,
+}
+
+/// A [Break] expression: `break` [`Expr`]?
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Break {
+    pub body: Option<Box<Expr>>,
+}
+
+/// A [Return] expression `return` [`Expr`]?
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Return {
+    pub body: Option<Box<Expr>>,
+}

compiler/cl-ast/src/ast_impl.rs

@@ -0,0 +1,8 @@
+//! Implementations of AST nodes and traits
+use super::*;
+
+mod convert;
+mod display;
+mod path;
+
+pub(crate) mod weight_of;

compiler/cl-ast/src/ast_impl/convert.rs

@@ -0,0 +1,162 @@
+//! Converts between major enums and enum variants
+use super::*;
+
+impl<T: AsRef<str>> From<T> for PathPart {
+    fn from(value: T) -> Self {
+        match value.as_ref() {
+            "super" => PathPart::SuperKw,
+            ident => PathPart::Ident(ident.into()),
+        }
+    }
+}
+
+macro impl_from ($(impl From for $T:ty {$($from:ty => $to:expr),*$(,)?})*) {$($(
+    impl From<$from> for $T {
+        fn from(value: $from) -> Self {
+            $to(value.into()) // Uses *tuple constructor*
+        }
+    }
+    impl From<Box<$from>> for $T {
+        fn from(value: Box<$from>) -> Self {
+            $to((*value).into())
+        }
+    }
+)*)*}
+
+impl_from! {
+    impl From for ItemKind {
+        Alias => ItemKind::Alias,
+        Const => ItemKind::Const,
+        Static => ItemKind::Static,
+        Module => ItemKind::Module,
+        Function => ItemKind::Function,
+        Struct => ItemKind::Struct,
+        Enum => ItemKind::Enum,
+        Impl => ItemKind::Impl,
+        Use => ItemKind::Use,
+    }
+    impl From for StructKind {
+        Vec<Ty> => StructKind::Tuple,
+        // TODO: Struct members in struct
+    }
+    impl From for TyKind {
+        Path => TyKind::Path,
+        TyTuple => TyKind::Tuple,
+        TyRef => TyKind::Ref,
+        TyPtr => TyKind::Ptr,
+        TyFn => TyKind::Fn,
+    }
+    impl From for StmtKind {
+        Item => StmtKind::Item,
+        Expr => StmtKind::Expr,
+    }
+    impl From for ExprKind {
+        Let => ExprKind::Let,
+        Closure => ExprKind::Closure,
+        Quote => ExprKind::Quote,
+        Match => ExprKind::Match,
+        Assign => ExprKind::Assign,
+        Modify => ExprKind::Modify,
+        Binary => ExprKind::Binary,
+        Unary => ExprKind::Unary,
+        Cast => ExprKind::Cast,
+        Member => ExprKind::Member,
+        Index => ExprKind::Index,
+        Path => ExprKind::Path,
+        Literal => ExprKind::Literal,
+        Array => ExprKind::Array,
+        ArrayRep => ExprKind::ArrayRep,
+        AddrOf => ExprKind::AddrOf,
+        Block => ExprKind::Block,
+        Group => ExprKind::Group,
+        Tuple => ExprKind::Tuple,
+        While => ExprKind::While,
+        If => ExprKind::If,
+        For => ExprKind::For,
+        Break => ExprKind::Break,
+        Return => ExprKind::Return,
+    }
+    impl From for Literal {
+        bool => Literal::Bool,
+        char => Literal::Char,
+        u128 => Literal::Int,
+        String => Literal::String,
+    }
+}
+
+impl From<Option<Expr>> for Else {
+    fn from(value: Option<Expr>) -> Self {
+        Self { body: value.map(Into::into) }
+    }
+}
+impl From<Expr> for Else {
+    fn from(value: Expr) -> Self {
+        Self { body: Some(value.into()) }
+    }
+}
+
+impl TryFrom<Expr> for Pattern {
+    type Error = Expr;
+
+    /// Performs the conversion. On failure, returns the *first* non-pattern subexpression.
+    fn try_from(value: Expr) -> Result<Self, Self::Error> {
+        Ok(match value.kind {
+            ExprKind::Literal(literal) => Pattern::Literal(literal),
+            ExprKind::Path(Path { absolute: false, ref parts }) => match parts.as_slice() {
+                [PathPart::Ident(name)] => Pattern::Name(*name),
+                _ => Err(value)?,
+            },
+            ExprKind::Empty => Pattern::Tuple(vec![]),
+            ExprKind::Group(Group { expr }) => Pattern::Tuple(vec![Pattern::try_from(*expr)?]),
+            ExprKind::Tuple(Tuple { exprs }) => Pattern::Tuple(
+                exprs
+                    .into_iter()
+                    .map(Pattern::try_from)
+                    .collect::<Result<_, _>>()?,
+            ),
+            ExprKind::AddrOf(AddrOf { mutable, expr }) => {
+                Pattern::Ref(mutable, Box::new(Pattern::try_from(*expr)?))
+            }
+            ExprKind::Array(Array { values }) => Pattern::Array(
+                values
+                    .into_iter()
+                    .map(Pattern::try_from)
+                    .collect::<Result<_, _>>()?,
+            ),
+            ExprKind::Binary(Binary { kind: BinaryKind::Call, parts }) => {
+                let (Expr { kind: ExprKind::Path(path), .. }, args) = *parts else {
+                    return Err(parts.0);
+                };
+                match args.kind {
+                    ExprKind::Empty | ExprKind::Tuple(_) => {}
+                    _ => return Err(args),
+                }
+                let Pattern::Tuple(args) = Pattern::try_from(args)? else {
+                    unreachable!("Arguments should be convertible to pattern!")
+                };
+                Pattern::TupleStruct(path, args)
+            }
+            ExprKind::Binary(Binary { kind: BinaryKind::RangeExc, parts }) => {
+                let (head, tail) = (Pattern::try_from(parts.0)?, Pattern::try_from(parts.1)?);
+                Pattern::RangeExc(head.into(), tail.into())
+            }
+            ExprKind::Binary(Binary { kind: BinaryKind::RangeInc, parts }) => {
+                let (head, tail) = (Pattern::try_from(parts.0)?, Pattern::try_from(parts.1)?);
+                Pattern::RangeInc(head.into(), tail.into())
+            }
+            ExprKind::Unary(Unary { kind: UnaryKind::RangeExc, tail }) => {
+                Pattern::Rest(Some(Pattern::try_from(*tail)?.into()))
+            }
+            ExprKind::Structor(Structor { to, init }) => {
+                let fields = init
+                    .into_iter()
+                    .map(|Fielder { name, init }| {
+                        Ok((name, init.map(|i| Pattern::try_from(*i)).transpose()?))
+                    })
+                    .collect::<Result<_, Self::Error>>()?;
+                Pattern::Struct(to, fields)
+            }
+            _ => Err(value)?,
+        })
+    }
+}

compiler/cl-ast/src/ast_impl/display.rs

@@ -0,0 +1,773 @@
+//! Implements [Display] for [AST](super::super) Types
+
+use super::*;
+use format::{delimiters::*, *};
+use std::{
+    borrow::Borrow,
+    fmt::{Display, Write},
+};
+
+fn separate<I: Display, W: Write>(
+    iterable: impl IntoIterator<Item = I>,
+    sep: &'static str,
+) -> impl FnOnce(W) -> std::fmt::Result {
+    move |mut f| {
+        for (idx, item) in iterable.into_iter().enumerate() {
+            if idx > 0 {
+                f.write_str(sep)?;
+            }
+            write!(f, "{item}")?;
+        }
+        Ok(())
+    }
+}
+
+impl Display for Mutability {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Mutability::Not => Ok(()),
+            Mutability::Mut => "mut ".fmt(f),
+        }
+    }
+}
+
+impl Display for Visibility {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Visibility::Private => Ok(()),
+            Visibility::Public => "pub ".fmt(f),
+        }
+    }
+}
+
+impl Display for Literal {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Literal::Bool(v) => v.fmt(f),
+            Literal::Char(v) => write!(f, "'{}'", v.escape_debug()),
+            Literal::Int(v) => v.fmt(f),
+            Literal::Float(v) => write!(f, "{:?}", f64::from_bits(*v)),
+            Literal::String(v) => write!(f, "\"{}\"", v.escape_debug()),
+        }
+    }
+}
+
+impl Display for File {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        separate(&self.items, "\n\n")(f)
+    }
+}
+
+impl Display for Attrs {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { meta } = self;
+        if meta.is_empty() {
+            return Ok(());
+        }
+        "#".fmt(f)?;
+        separate(meta, ", ")(&mut f.delimit(INLINE_SQUARE))?;
+        "\n".fmt(f)
+    }
+}
+
+impl Display for Meta {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { name, kind } = self;
+        write!(f, "{name}{kind}")
+    }
+}
+
+impl Display for MetaKind {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            MetaKind::Plain => Ok(()),
+            MetaKind::Equals(v) => write!(f, " = {v}"),
+            MetaKind::Func(args) => separate(args, ", ")(f.delimit(INLINE_PARENS)),
+        }
+    }
+}
+
+impl Display for Item {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { span: _, attrs, vis, kind } = self;
+        attrs.fmt(f)?;
+        vis.fmt(f)?;
+        kind.fmt(f)
+    }
+}
+
+impl Display for ItemKind {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            ItemKind::Alias(v) => v.fmt(f),
+            ItemKind::Const(v) => v.fmt(f),
+            ItemKind::Static(v) => v.fmt(f),
+            ItemKind::Module(v) => v.fmt(f),
+            ItemKind::Function(v) => v.fmt(f),
+            ItemKind::Struct(v) => v.fmt(f),
+            ItemKind::Enum(v) => v.fmt(f),
+            ItemKind::Impl(v) => v.fmt(f),
+            ItemKind::Use(v) => v.fmt(f),
+        }
+    }
+}
+
+impl Display for Generics {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Generics { vars } = self;
+        if !vars.is_empty() {
+            separate(vars, ", ")(f.delimit_with("<", ">"))?
+        }
+        Ok(())
+    }
+}
+
+impl Display for Alias {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { name, from } = self;
+        match from {
+            Some(from) => write!(f, "type {name} = {from};"),
+            None => write!(f, "type {name};"),
+        }
+    }
+}
+
+impl Display for Const {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { name, ty, init } = self;
+        write!(f, "const {name}: {ty} = {init}")
+    }
+}
+
+impl Display for Static {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { mutable, name, ty, init } = self;
+        write!(f, "static {mutable}{name}: {ty} = {init}")
+    }
+}
+
+impl Display for Module {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { name, file } = self;
+        write!(f, "mod {name}")?;
+        match file {
+            Some(items) => {
+                ' '.fmt(f)?;
+                write!(f.delimit(BRACES), "{items}")
+            }
+            None => Ok(()),
+        }
+    }
+}
+
+impl Display for Function {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { name, gens, sign: sign @ TyFn { args, rety }, bind, body } = self;
+        let types = match args.kind {
+            TyKind::Tuple(TyTuple { ref types }) => types.as_slice(),
+            _ => {
+                write!(f, "Invalid function signature: {sign}")?;
+                Default::default()
+            }
+        };
+        let bind = match bind {
+            Pattern::Tuple(patterns) => patterns.as_slice(),
+            _ => {
+                write!(f, "Invalid argument binder: {bind}")?;
+                Default::default()
+            }
+        };
+
+        debug_assert_eq!(bind.len(), types.len());
+        write!(f, "fn {name}{gens} ")?;
+        {
+            let mut f = f.delimit(INLINE_PARENS);
+
+            for (idx, (arg, ty)) in bind.iter().zip(types.iter()).enumerate() {
+                if idx != 0 {
+                    f.write_str(", ")?;
+                }
+                write!(f, "{arg}: {ty}")?;
+            }
+        }
+        if let TyKind::Tuple(TyTuple { types }) = &rety.kind
+            && !types.as_slice().is_empty()
+        {
+            write!(f, " -> {rety}")?
+        }
+
+        match body {
+            Some(body) => write!(f, " {body}"),
+            None => ';'.fmt(f),
+        }
+    }
+}
+
+impl Display for Struct {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { name, gens, kind } = self;
+        write!(f, "struct {name}{gens}{kind}")
+    }
+}
+
+impl Display for StructKind {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            StructKind::Empty => ';'.fmt(f),
+            StructKind::Tuple(v) => separate(v, ", ")(f.delimit(INLINE_PARENS)),
+            StructKind::Struct(v) => separate(v, ",\n")(f.delimit(SPACED_BRACES)),
+        }
+    }
+}
+
+impl Display for StructMember {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { vis, name, ty } = self;
+        write!(f, "{vis}{name}: {ty}")
+    }
+}
+
+impl Display for Enum {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { name, gens, variants } = self;
+        write!(f, "enum {name}{gens}")?;
+        separate(variants, ",\n")(f.delimit(SPACED_BRACES))
+    }
+}
+
+impl Display for Variant {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { name, kind, body } = self;
+        write!(f, "{name}{kind}")?;
+        match body {
+            Some(body) => write!(f, " {body}"),
+            None => Ok(()),
+        }
+    }
+}
+
+impl Display for Impl {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { gens, target, body } = self;
+        write!(f, "impl{gens} {target} ")?;
+        write!(f.delimit(BRACES), "{body}")
+    }
+}
+
+impl Display for ImplKind {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            ImplKind::Type(t) => t.fmt(f),
+            ImplKind::Trait { impl_trait, for_type } => {
+                write!(f, "{impl_trait} for {for_type}")
+            }
+        }
+    }
+}
+
+impl Display for Use {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { absolute, tree } = self;
+        f.write_str(if *absolute { "use ::" } else { "use " })?;
+        write!(f, "{tree};")
+    }
+}
+
+impl Display for UseTree {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            UseTree::Tree(tree) => separate(tree, ", ")(f.delimit(INLINE_BRACES)),
+            UseTree::Path(path, rest) => write!(f, "{path}::{rest}"),
+            UseTree::Alias(path, name) => write!(f, "{path} as {name}"),
+            UseTree::Name(name) => write!(f, "{name}"),
+            UseTree::Glob => write!(f, "*"),
+        }
+    }
+}
+
+impl Display for Ty {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { span: _, kind, gens } = self;
+        write!(f, "{kind}{gens}")
+    }
+}
+
+impl Display for TyKind {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            TyKind::Never => "!".fmt(f),
+            TyKind::Infer => "_".fmt(f),
+            TyKind::Path(v) => v.fmt(f),
+            TyKind::Array(v) => v.fmt(f),
+            TyKind::Slice(v) => v.fmt(f),
+            TyKind::Tuple(v) => v.fmt(f),
+            TyKind::Ref(v) => v.fmt(f),
+            TyKind::Ptr(v) => v.fmt(f),
+            TyKind::Fn(v) => v.fmt(f),
+        }
+    }
+}
+
+impl Display for TyArray {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { ty, count } = self;
+        write!(f, "[{ty}; {count}]")
+    }
+}
+
+impl Display for TySlice {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { ty } = self;
+        write!(f, "[{ty}]")
+    }
+}
+
+impl Display for TyTuple {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        separate(&self.types, ", ")(f.delimit(INLINE_PARENS))
+    }
+}
+
+impl Display for TyRef {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let &Self { count, mutable, ref to } = self;
+        for _ in 0..count {
+            f.write_char('&')?;
+        }
+        write!(f, "{mutable}{to}")
+    }
+}
+
+impl Display for TyPtr {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { to } = self;
+        write!(f, "*{to}")
+    }
+}
+
+impl Display for TyFn {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { args, rety } = self;
+        write!(f, "fn {args}")?;
+        if let TyKind::Tuple(TyTuple { types }) = &rety.kind
+            && !types.as_slice().is_empty()
+        {
+            write!(f, " -> {rety}")?
+        }
+        Ok(())
+    }
+}
+
+impl Display for Path {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { absolute, parts } = self;
+        if *absolute {
+            "::".fmt(f)?;
+        }
+        separate(parts, "::")(f)
+    }
+}
+
+impl Display for PathPart {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            PathPart::SuperKw => "super".fmt(f),
+            PathPart::SelfTy => "Self".fmt(f),
+            PathPart::Ident(id) => id.fmt(f),
+        }
+    }
+}
+
+impl Display for Stmt {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Stmt { span: _, kind, semi } = self;
+        write!(f, "{kind}{semi}")
+    }
+}
+
+impl Display for StmtKind {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            StmtKind::Empty => Ok(()),
+            StmtKind::Item(v) => v.fmt(f),
+            StmtKind::Expr(v) => v.fmt(f),
+        }
+    }
+}
+
+impl Display for Semi {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Semi::Terminated => ';'.fmt(f),
+            Semi::Unterminated => Ok(()),
+        }
+    }
+}
+
+impl Display for Expr {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.kind.fmt(f)
+    }
+}
+
+impl Display for ExprKind {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            ExprKind::Empty => "()".fmt(f),
+            ExprKind::Closure(v) => v.fmt(f),
+            ExprKind::Quote(v) => v.fmt(f),
+            ExprKind::Let(v) => v.fmt(f),
+            ExprKind::Match(v) => v.fmt(f),
+            ExprKind::Assign(v) => v.fmt(f),
+            ExprKind::Modify(v) => v.fmt(f),
+            ExprKind::Binary(v) => v.fmt(f),
+            ExprKind::Unary(v) => v.fmt(f),
+            ExprKind::Cast(v) => v.fmt(f),
+            ExprKind::Member(v) => v.fmt(f),
+            ExprKind::Index(v) => v.fmt(f),
+            ExprKind::Structor(v) => v.fmt(f),
+            ExprKind::Path(v) => v.fmt(f),
+            ExprKind::Literal(v) => v.fmt(f),
+            ExprKind::Array(v) => v.fmt(f),
+            ExprKind::ArrayRep(v) => v.fmt(f),
+            ExprKind::AddrOf(v) => v.fmt(f),
+            ExprKind::Block(v) => v.fmt(f),
+            ExprKind::Group(v) => v.fmt(f),
+            ExprKind::Tuple(v) => v.fmt(f),
+            ExprKind::While(v) => v.fmt(f),
+            ExprKind::If(v) => v.fmt(f),
+            ExprKind::For(v) => v.fmt(f),
+            ExprKind::Break(v) => v.fmt(f),
+            ExprKind::Return(v) => v.fmt(f),
+            ExprKind::Continue => "continue".fmt(f),
+        }
+    }
+}
+
+impl Display for Closure {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { arg, body } = self;
+        match arg.as_ref() {
+            Pattern::Tuple(args) => separate(args, ", ")(f.delimit_with("|", "|")),
+            _ => arg.fmt(f),
+        }?;
+        write!(f, " {body}")
+    }
+}
+
+impl Display for Quote {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { quote } = self;
+        write!(f, "`{quote}`")
+    }
+}
+
+impl Display for Let {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { mutable, name, ty, init } = self;
+        write!(f, "let {mutable}{name}")?;
+        if let Some(value) = ty {
+            write!(f, ": {value}")?;
+        }
+        if let Some(value) = init {
+            write!(f, " = {value}")?;
+        }
+        Ok(())
+    }
+}
+
+impl Display for Pattern {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Pattern::Name(sym) => sym.fmt(f),
+            Pattern::Path(path) => path.fmt(f),
+            Pattern::Literal(literal) => literal.fmt(f),
+            Pattern::Rest(Some(name)) => write!(f, "..{name}"),
+            Pattern::Rest(None) => "..".fmt(f),
+            Pattern::Ref(mutability, pattern) => write!(f, "&{mutability}{pattern}"),
+            Pattern::RangeExc(head, tail) => write!(f, "{head}..{tail}"),
+            Pattern::RangeInc(head, tail) => write!(f, "{head}..={tail}"),
+            Pattern::Tuple(patterns) => separate(patterns, ", ")(f.delimit(INLINE_PARENS)),
+            Pattern::Array(patterns) => separate(patterns, ", ")(f.delimit(INLINE_SQUARE)),
+            Pattern::Struct(path, items) => {
+                write!(f, "{path} ")?;
+                let f = &mut f.delimit(INLINE_BRACES);
+                for (idx, (name, item)) in items.iter().enumerate() {
+                    if idx != 0 {
+                        f.write_str(", ")?;
+                    }
+                    write!(f, "{name}")?;
+                    if let Some(pattern) = item {
+                        write!(f, ": {pattern}")?
+                    }
+                }
+                Ok(())
+            }
+            Pattern::TupleStruct(path, items) => {
+                write!(f, "{path}")?;
+                separate(items, ", ")(f.delimit(INLINE_PARENS))
+            }
+        }
+    }
+}
+
+impl Display for Match {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { scrutinee, arms } = self;
+        write!(f, "match {scrutinee} ")?;
+        separate(arms, ",\n")(f.delimit(BRACES))
+    }
+}
+
+impl Display for MatchArm {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self(pat, expr) = self;
+        write!(f, "{pat} => {expr}")
+    }
+}
+
+impl Display for Assign {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { parts } = self;
+        write!(f, "{} = {}", parts.0, parts.1)
+    }
+}
+
+impl Display for Modify {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { kind, parts } = self;
+        write!(f, "{} {kind} {}", parts.0, parts.1)
+    }
+}
+
+impl Display for ModifyKind {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            ModifyKind::Mul => "*=",
+            ModifyKind::Div => "/=",
+            ModifyKind::Rem => "%=",
+            ModifyKind::Add => "+=",
+            ModifyKind::Sub => "-=",
+            ModifyKind::And => "&=",
+            ModifyKind::Or => "|=",
+            ModifyKind::Xor => "^=",
+            ModifyKind::Shl => "<<=",
+            ModifyKind::Shr => ">>=",
+        }
+        .fmt(f)
+    }
+}
+
+impl Display for Binary {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { kind, parts } = self;
+        let (head, tail) = parts.borrow();
+        match kind {
+            BinaryKind::Call => write!(f, "{head}{tail}"),
+            _ => write!(f, "{head} {kind} {tail}"),
+        }
+    }
+}
+
+impl Display for BinaryKind {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            BinaryKind::Lt => "<",
+            BinaryKind::LtEq => "<=",
+            BinaryKind::Equal => "==",
+            BinaryKind::NotEq => "!=",
+            BinaryKind::GtEq => ">=",
+            BinaryKind::Gt => ">",
+            BinaryKind::RangeExc => "..",
+            BinaryKind::RangeInc => "..=",
+            BinaryKind::LogAnd => "&&",
+            BinaryKind::LogOr => "||",
+            BinaryKind::LogXor => "^^",
+            BinaryKind::BitAnd => "&",
+            BinaryKind::BitOr => "|",
+            BinaryKind::BitXor => "^",
+            BinaryKind::Shl => "<<",
+            BinaryKind::Shr => ">>",
+            BinaryKind::Add => "+",
+            BinaryKind::Sub => "-",
+            BinaryKind::Mul => "*",
+            BinaryKind::Div => "/",
+            BinaryKind::Rem => "%",
+            BinaryKind::Call => "()",
+        }
+        .fmt(f)
+    }
+}
+
+impl Display for Unary {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { kind, tail } = self;
+        write!(f, "{kind}{tail}")
+    }
+}
+
+impl Display for UnaryKind {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            UnaryKind::Loop => "loop ",
+            UnaryKind::Deref => "*",
+            UnaryKind::Neg => "-",
+            UnaryKind::Not => "!",
+            UnaryKind::RangeExc => "..",
+            UnaryKind::RangeInc => "..=",
+            UnaryKind::At => "@",
+            UnaryKind::Tilde => "~",
+        }
+        .fmt(f)
+    }
+}
+
+impl Display for Cast {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { head, ty } = self;
+        write!(f, "{head} as {ty}")
+    }
+}
+
+impl Display for Member {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { head, kind } = self;
+        write!(f, "{head}.{kind}")
+    }
+}
+
+impl Display for MemberKind {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            MemberKind::Call(name, args) => write!(f, "{name}{args}"),
+            MemberKind::Struct(name) => write!(f, "{name}"),
+            MemberKind::Tuple(name) => write!(f, "{name}"),
+        }
+    }
+}
+
+impl Display for Index {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { head, indices } = self;
+        write!(f, "{head}")?;
+        separate(indices, ", ")(f.delimit(INLINE_SQUARE))
+    }
+}
+
+impl Display for Structor {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { to, init } = self;
+        write!(f, "{to} ")?;
+        separate(init, ", ")(f.delimit(INLINE_BRACES))
+    }
+}
+
+impl Display for Fielder {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { name, init } = self;
+        write!(f, "{name}")?;
+        if let Some(init) = init {
+            write!(f, ": {init}")?;
+        }
+        Ok(())
+    }
+}
+
+impl Display for Array {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        separate(&self.values, ", ")(f.delimit(INLINE_SQUARE))
+    }
+}
+
+impl Display for ArrayRep {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { value, repeat } = self;
+        write!(f, "[{value}; {repeat}]")
+    }
+}
+
+impl Display for AddrOf {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { mutable, expr } = self;
+        write!(f, "&{mutable}{expr}")
+    }
+}
+
+impl Display for Block {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { stmts } = self;
+
+        match stmts.as_slice() {
+            [] => "{}".fmt(f),
+            stmts => separate(stmts, "\n")(f.delimit(BRACES)),
+        }
+    }
+}
+
+impl Display for Group {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "({})", self.expr)
+    }
+}
+
+impl Display for Tuple {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { exprs } = self;
+
+        match exprs.as_slice() {
+            [] => write!(f, "()"),
+            [expr] => write!(f, "({expr},)"),
+            exprs => separate(exprs, ", ")(f.delimit(INLINE_PARENS)),
+        }
+    }
+}
+
+impl Display for While {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { cond, pass, fail } = self;
+        write!(f, "while {cond} {pass}{fail}")
+    }
+}
+
+impl Display for If {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { cond, pass, fail } = self;
+        write!(f, "if {cond} {pass}{fail}")
+    }
+}
+
+impl Display for For {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { bind, cond, pass, fail } = self;
+        write!(f, "for {bind} in {cond} {pass}{fail}")
+    }
+}
+
+impl Display for Else {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match &self.body {
+            Some(body) => write!(f, " else {body}"),
+            _ => Ok(()),
+        }
+    }
+}
+
+impl Display for Break {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "break")?;
+        match &self.body {
+            Some(body) => write!(f, " {body}"),
+            _ => Ok(()),
+        }
+    }
+}
+
+impl Display for Return {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "return")?;
+        match &self.body {
+            Some(body) => write!(f, " {body}"),
+            _ => Ok(()),
+        }
+    }
+}

compiler/cl-ast/src/ast_impl/path.rs

@@ -0,0 +1,60 @@
+//! Utils for [Path]
+use crate::{PathPart, Sym, ast::Path};
+
+impl Path {
+    /// Appends a [PathPart] to this [Path]
+    pub fn push(&mut self, part: PathPart) {
+        self.parts.push(part);
+    }
+    /// Removes a [PathPart] from this [Path]
+    pub fn pop(&mut self) -> Option<PathPart> {
+        self.parts.pop()
+    }
+    /// Concatenates `self::other`. If `other` is an absolute [Path],
+    /// this replaces `self` with `other`
+    pub fn concat(mut self, other: &Self) -> Self {
+        if other.absolute {
+            other.clone()
+        } else {
+            self.parts.extend(other.parts.iter().cloned());
+            self
+        }
+    }
+
+    /// Gets the defining [Sym] of this path
+    pub fn as_sym(&self) -> Option<Sym> {
+        match self.parts.as_slice() {
+            [.., PathPart::Ident(name)] => Some(*name),
+            _ => None,
+        }
+    }
+
+    /// Checks whether this path ends in the given [Sym]
+    pub fn ends_with(&self, name: &str) -> bool {
+        match self.parts.as_slice() {
+            [.., PathPart::Ident(last)] => name == &**last,
+            _ => false,
+        }
+    }
+
+    /// Checks whether this path refers to the sinkhole identifier, `_`
+    pub fn is_sinkhole(&self) -> bool {
+        if let [PathPart::Ident(id)] = self.parts.as_slice()
+            && let "_" = id.to_ref()
+        {
+            return true;
+        }
+        false
+    }
+}
+impl PathPart {
+    pub fn from_sym(ident: Sym) -> Self {
+        Self::Ident(ident)
+    }
+}
+
+impl From<Sym> for Path {
+    fn from(value: Sym) -> Self {
+        Self { parts: vec![PathPart::Ident(value)], absolute: false }
+    }
+}

compiler/cl-ast/src/ast_impl/weight_of.rs

@@ -0,0 +1,617 @@
+//! Approximates the size of an AST
+
+use std::mem::size_of_val;
+
+use crate::ast::*;
+use cl_structures::{intern::interned::Interned, span::Span};
+
+/// Approximates the size of an AST without including indirection (pointers) or padding
+pub trait WeightOf {
+    /// Approximates the size of a syntax tree without including pointer/indirection or padding.
+    fn weight_of(&self) -> usize;
+}
+
+impl WeightOf for File {
+    fn weight_of(&self) -> usize {
+        let Self { name, items } = self;
+        name.weight_of() + items.weight_of()
+    }
+}
+
+impl WeightOf for Attrs {
+    fn weight_of(&self) -> usize {
+        let Self { meta } = self;
+        meta.weight_of()
+    }
+}
+
+impl WeightOf for Meta {
+    fn weight_of(&self) -> usize {
+        let Self { name, kind } = self;
+        name.weight_of() + kind.weight_of()
+    }
+}
+
+impl WeightOf for MetaKind {
+    fn weight_of(&self) -> usize {
+        match self {
+            MetaKind::Plain => size_of_val(self),
+            MetaKind::Equals(v) => v.weight_of(),
+            MetaKind::Func(v) => v.weight_of(),
+        }
+    }
+}
+
+impl WeightOf for Item {
+    fn weight_of(&self) -> usize {
+        let Self { span, attrs, vis, kind } = self;
+        span.weight_of() + attrs.weight_of() + vis.weight_of() + kind.weight_of()
+    }
+}
+
+impl WeightOf for ItemKind {
+    fn weight_of(&self) -> usize {
+        match self {
+            ItemKind::Module(v) => v.weight_of(),
+            ItemKind::Alias(v) => v.weight_of(),
+            ItemKind::Enum(v) => v.weight_of(),
+            ItemKind::Struct(v) => v.weight_of(),
+            ItemKind::Const(v) => v.weight_of(),
+            ItemKind::Static(v) => v.weight_of(),
+            ItemKind::Function(v) => v.weight_of(),
+            ItemKind::Impl(v) => v.weight_of(),
+            ItemKind::Use(v) => v.weight_of(),
+        }
+    }
+}
+
+impl WeightOf for Generics {
+    fn weight_of(&self) -> usize {
+        let Self { vars } = self;
+        vars.iter().map(|v| v.weight_of()).sum()
+    }
+}
+
+impl WeightOf for Module {
+    fn weight_of(&self) -> usize {
+        let Self { name, file } = self;
+        name.weight_of() + file.weight_of()
+    }
+}
+
+impl WeightOf for Alias {
+    fn weight_of(&self) -> usize {
+        let Self { name, from } = self;
+        name.weight_of() + from.weight_of()
+    }
+}
+
+impl WeightOf for Const {
+    fn weight_of(&self) -> usize {
+        let Self { name, ty, init } = self;
+        name.weight_of() + ty.weight_of() + init.weight_of()
+    }
+}
+
+impl WeightOf for Static {
+    fn weight_of(&self) -> usize {
+        let Self { mutable, name, ty, init } = self;
+        mutable.weight_of() + name.weight_of() + ty.weight_of() + init.weight_of()
+    }
+}
+
+impl WeightOf for Function {
+    fn weight_of(&self) -> usize {
+        let Self { name, gens, sign, bind, body } = self;
+        name.weight_of() + gens.weight_of() + sign.weight_of() + bind.weight_of() + body.weight_of()
+    }
+}
+
+impl WeightOf for Struct {
+    fn weight_of(&self) -> usize {
+        let Self { name, gens, kind } = self;
+        name.weight_of() + gens.weight_of() + kind.weight_of()
+    }
+}
+
+impl WeightOf for StructKind {
+    fn weight_of(&self) -> usize {
+        match self {
+            StructKind::Empty => size_of_val(self),
+            StructKind::Tuple(items) => items.weight_of(),
+            StructKind::Struct(sm) => sm.weight_of(),
+        }
+    }
+}
+
+impl WeightOf for StructMember {
+    fn weight_of(&self) -> usize {
+        let Self { vis, name, ty } = self;
+        vis.weight_of() + name.weight_of() + ty.weight_of()
+    }
+}
+
+impl WeightOf for Enum {
+    fn weight_of(&self) -> usize {
+        let Self { name, gens, variants } = self;
+        name.weight_of() + gens.weight_of() + variants.weight_of()
+    }
+}
+
+impl WeightOf for Variant {
+    fn weight_of(&self) -> usize {
+        let Self { name, kind, body } = self;
+        name.weight_of() + kind.weight_of() + body.weight_of()
+    }
+}
+
+impl WeightOf for Impl {
+    fn weight_of(&self) -> usize {
+        let Self { gens, target, body } = self;
+        gens.weight_of() + target.weight_of() + body.weight_of()
+    }
+}
+
+impl WeightOf for ImplKind {
+    fn weight_of(&self) -> usize {
+        match self {
+            ImplKind::Type(ty) => ty.weight_of(),
+            ImplKind::Trait { impl_trait, for_type } => {
+                impl_trait.weight_of() + for_type.weight_of()
+            }
+        }
+    }
+}
+
+impl WeightOf for Use {
+    fn weight_of(&self) -> usize {
+        let Self { absolute, tree } = self;
+        absolute.weight_of() + tree.weight_of()
+    }
+}
+
+impl WeightOf for UseTree {
+    fn weight_of(&self) -> usize {
+        match self {
+            UseTree::Tree(tr) => tr.weight_of(),
+            UseTree::Path(pa, tr) => pa.weight_of() + tr.weight_of(),
+            UseTree::Alias(src, dst) => src.weight_of() + dst.weight_of(),
+            UseTree::Name(src) => src.weight_of(),
+            UseTree::Glob => size_of_val(self),
+        }
+    }
+}
+
+impl WeightOf for Ty {
+    fn weight_of(&self) -> usize {
+        let Self { span, kind, gens } = self;
+        span.weight_of() + kind.weight_of() + gens.weight_of()
+    }
+}
+
+impl WeightOf for TyKind {
+    fn weight_of(&self) -> usize {
+        match self {
+            TyKind::Never | TyKind::Infer => size_of_val(self),
+            TyKind::Path(v) => v.weight_of(),
+            TyKind::Array(v) => v.weight_of(),
+            TyKind::Slice(v) => v.weight_of(),
+            TyKind::Tuple(v) => v.weight_of(),
+            TyKind::Ref(v) => v.weight_of(),
+            TyKind::Ptr(v) => v.weight_of(),
+            TyKind::Fn(v) => v.weight_of(),
+        }
+    }
+}
+
+impl WeightOf for TyArray {
+    fn weight_of(&self) -> usize {
+        let Self { ty, count } = self;
+        ty.weight_of() + count.weight_of()
+    }
+}
+
+impl WeightOf for TySlice {
+    fn weight_of(&self) -> usize {
+        let Self { ty } = self;
+        ty.weight_of()
+    }
+}
+
+impl WeightOf for TyTuple {
+    fn weight_of(&self) -> usize {
+        let Self { types } = self;
+        types.weight_of()
+    }
+}
+
+impl WeightOf for TyRef {
+    fn weight_of(&self) -> usize {
+        let Self { mutable, count, to } = self;
+        mutable.weight_of() + count.weight_of() + to.weight_of()
+    }
+}
+
+impl WeightOf for TyPtr {
+    fn weight_of(&self) -> usize {
+        let Self { to } = self;
+        to.weight_of()
+    }
+}
+
+impl WeightOf for TyFn {
+    fn weight_of(&self) -> usize {
+        let Self { args, rety } = self;
+        args.weight_of() + rety.weight_of()
+    }
+}
+
+impl WeightOf for Path {
+    fn weight_of(&self) -> usize {
+        let Self { absolute, parts } = self;
+        absolute.weight_of() + parts.weight_of()
+    }
+}
+
+impl WeightOf for PathPart {
+    fn weight_of(&self) -> usize {
+        match self {
+            PathPart::SuperKw => size_of_val(self),
+            PathPart::SelfTy => size_of_val(self),
+            PathPart::Ident(interned) => interned.weight_of(),
+        }
+    }
+}
+
+impl WeightOf for Stmt {
+    fn weight_of(&self) -> usize {
+        let Self { span, kind, semi } = self;
+        span.weight_of() + kind.weight_of() + semi.weight_of()
+    }
+}
+
+impl WeightOf for StmtKind {
+    fn weight_of(&self) -> usize {
+        match self {
+            StmtKind::Empty => size_of_val(self),
+            StmtKind::Item(item) => item.weight_of(),
+            StmtKind::Expr(expr) => expr.weight_of(),
+        }
+    }
+}
+
+impl WeightOf for Expr {
+    fn weight_of(&self) -> usize {
+        let Self { span, kind } = self;
+        span.weight_of() + kind.weight_of()
+    }
+}
+
+impl WeightOf for ExprKind {
+    fn weight_of(&self) -> usize {
+        match self {
+            ExprKind::Empty => size_of_val(self),
+            ExprKind::Closure(v) => v.weight_of(),
+            ExprKind::Quote(v) => v.weight_of(),
+            ExprKind::Let(v) => v.weight_of(),
+            ExprKind::Match(v) => v.weight_of(),
+            ExprKind::Assign(v) => v.weight_of(),
+            ExprKind::Modify(v) => v.weight_of(),
+            ExprKind::Binary(v) => v.weight_of(),
+            ExprKind::Unary(v) => v.weight_of(),
+            ExprKind::Cast(v) => v.weight_of(),
+            ExprKind::Member(v) => v.weight_of(),
+            ExprKind::Index(v) => v.weight_of(),
+            ExprKind::Structor(v) => v.weight_of(),
+            ExprKind::Path(v) => v.weight_of(),
+            ExprKind::Literal(v) => v.weight_of(),
+            ExprKind::Array(v) => v.weight_of(),
+            ExprKind::ArrayRep(v) => v.weight_of(),
+            ExprKind::AddrOf(v) => v.weight_of(),
+            ExprKind::Block(v) => v.weight_of(),
+            ExprKind::Group(v) => v.weight_of(),
+            ExprKind::Tuple(v) => v.weight_of(),
+            ExprKind::While(v) => v.weight_of(),
+            ExprKind::If(v) => v.weight_of(),
+            ExprKind::For(v) => v.weight_of(),
+            ExprKind::Break(v) => v.weight_of(),
+            ExprKind::Return(v) => v.weight_of(),
+            ExprKind::Continue => size_of_val(self),
+        }
+    }
+}
+
+impl WeightOf for Closure {
+    fn weight_of(&self) -> usize {
+        let Self { arg, body } = self;
+        arg.weight_of() + body.weight_of()
+    }
+}
+
+impl WeightOf for Quote {
+    fn weight_of(&self) -> usize {
+        let Self { quote } = self;
+        quote.weight_of()
+    }
+}
+
+impl WeightOf for Let {
+    fn weight_of(&self) -> usize {
+        let Self { mutable, name, ty, init } = self;
+        mutable.weight_of() + name.weight_of() + ty.weight_of() + init.weight_of()
+    }
+}
+
+impl WeightOf for Pattern {
+    fn weight_of(&self) -> usize {
+        match self {
+            Pattern::Name(s) => size_of_val(s),
+            Pattern::Path(p) => p.weight_of(),
+            Pattern::Literal(literal) => literal.weight_of(),
+            Pattern::Rest(Some(pattern)) => pattern.weight_of(),
+            Pattern::Rest(None) => 0,
+            Pattern::Ref(mutability, pattern) => mutability.weight_of() + pattern.weight_of(),
+            Pattern::RangeExc(head, tail) => head.weight_of() + tail.weight_of(),
+            Pattern::RangeInc(head, tail) => head.weight_of() + tail.weight_of(),
+            Pattern::Tuple(patterns) | Pattern::Array(patterns) => patterns.weight_of(),
+            Pattern::Struct(path, items) => {
+                let sitems: usize = items
+                    .iter()
+                    .map(|(name, opt)| name.weight_of() + opt.weight_of())
+                    .sum();
+                path.weight_of() + sitems
+            }
+            Pattern::TupleStruct(path, patterns) => path.weight_of() + patterns.weight_of(),
+        }
+    }
+}
+
+impl WeightOf for Match {
+    fn weight_of(&self) -> usize {
+        let Self { scrutinee, arms } = self;
+        scrutinee.weight_of() + arms.weight_of()
+    }
+}
+
+impl WeightOf for MatchArm {
+    fn weight_of(&self) -> usize {
+        let Self(pattern, expr) = self;
+        pattern.weight_of() + expr.weight_of()
+    }
+}
+
+impl WeightOf for Assign {
+    fn weight_of(&self) -> usize {
+        let Self { parts } = self;
+
+        parts.0.weight_of() + parts.1.weight_of()
+    }
+}
+
+impl WeightOf for Modify {
+    #[rustfmt::skip]
+    fn weight_of(&self) -> usize {
+        let Self { kind, parts } = self;
+        kind.weight_of()
+            + parts.0.weight_of()
+            + parts.1.weight_of()
+    }
+}
+
+impl WeightOf for Binary {
+    fn weight_of(&self) -> usize {
+        let Self { kind, parts } = self;
+
+        kind.weight_of() + parts.0.weight_of() + parts.1.weight_of()
+    }
+}
+
+impl WeightOf for Unary {
+    #[rustfmt::skip]
+    fn weight_of(&self) -> usize {
+        let Self { kind, tail } = self;
+         kind.weight_of() + tail.weight_of()
+    }
+}
+
+impl WeightOf for Cast {
+    fn weight_of(&self) -> usize {
+        let Self { head, ty } = self;
+        head.weight_of() + ty.weight_of()
+    }
+}
+
+impl WeightOf for Member {
+    fn weight_of(&self) -> usize {
+        let Self { head, kind } = self;
+
+        head.weight_of() + kind.weight_of() // accounting
+    }
+}
+
+impl WeightOf for MemberKind {
+    fn weight_of(&self) -> usize {
+        match self {
+            MemberKind::Call(_, tuple) => tuple.weight_of(),
+            MemberKind::Struct(_) => 0,
+            MemberKind::Tuple(literal) => literal.weight_of(),
+        }
+    }
+}
+
+impl WeightOf for Index {
+    fn weight_of(&self) -> usize {
+        let Self { head, indices } = self;
+        head.weight_of() + indices.weight_of()
+    }
+}
+
+impl WeightOf for Literal {
+    fn weight_of(&self) -> usize {
+        match self {
+            Literal::Bool(v) => v.weight_of(),
+            Literal::Char(v) => v.weight_of(),
+            Literal::Int(v) => v.weight_of(),
+            Literal::Float(v) => v.weight_of(),
+            Literal::String(v) => v.weight_of(),
+        }
+    }
+}
+
+impl WeightOf for Structor {
+    fn weight_of(&self) -> usize {
+        let Self { to, init } = self;
+        to.weight_of() + init.weight_of()
+    }
+}
+
+impl WeightOf for Fielder {
+    fn weight_of(&self) -> usize {
+        let Self { name, init } = self;
+        name.weight_of() + init.weight_of()
+    }
+}
+
+impl WeightOf for Array {
+    fn weight_of(&self) -> usize {
+        let Self { values } = self;
+        values.weight_of()
+    }
+}
+
+impl WeightOf for ArrayRep {
+    fn weight_of(&self) -> usize {
+        let Self { value, repeat } = self;
+        value.weight_of() + repeat.weight_of()
+    }
+}
+
+impl WeightOf for AddrOf {
+    fn weight_of(&self) -> usize {
+        let Self { mutable, expr } = self;
+        mutable.weight_of() + expr.weight_of()
+    }
+}
+
+impl WeightOf for Block {
+    fn weight_of(&self) -> usize {
+        let Self { stmts } = self;
+        stmts.weight_of()
+    }
+}
+
+impl WeightOf for Group {
+    fn weight_of(&self) -> usize {
+        let Self { expr } = self;
+        expr.weight_of()
+    }
+}
+
+impl WeightOf for Tuple {
+    fn weight_of(&self) -> usize {
+        let Self { exprs } = self;
+        exprs.weight_of()
+    }
+}
+
+impl WeightOf for While {
+    fn weight_of(&self) -> usize {
+        let Self { cond, pass, fail } = self;
+        cond.weight_of() + pass.weight_of() + fail.weight_of()
+    }
+}
+
+impl WeightOf for If {
+    fn weight_of(&self) -> usize {
+        let Self { cond, pass, fail } = self;
+        cond.weight_of() + pass.weight_of() + fail.weight_of()
+    }
+}
+
+impl WeightOf for For {
+    fn weight_of(&self) -> usize {
+        let Self { bind, cond, pass, fail } = self;
+        bind.weight_of() + cond.weight_of() + pass.weight_of() + fail.weight_of()
+    }
+}
+
+impl WeightOf for Else {
+    fn weight_of(&self) -> usize {
+        let Self { body } = self;
+        body.weight_of()
+    }
+}
+
+impl WeightOf for Break {
+    fn weight_of(&self) -> usize {
+        let Self { body } = self;
+        body.weight_of()
+    }
+}
+
+impl WeightOf for Return {
+    fn weight_of(&self) -> usize {
+        let Self { body } = self;
+        body.weight_of()
+    }
+}
+
+// ------------ SizeOf Blanket Implementations
+
+impl<T: WeightOf> WeightOf for Option<T> {
+    fn weight_of(&self) -> usize {
+        match self {
+            Some(t) => t.weight_of().max(size_of_val(t)),
+            None => size_of_val(self),
+        }
+    }
+}
+
+impl<T: WeightOf> WeightOf for [T] {
+    fn weight_of(&self) -> usize {
+        self.iter().map(WeightOf::weight_of).sum()
+    }
+}
+
+impl<T: WeightOf> WeightOf for Vec<T> {
+    fn weight_of(&self) -> usize {
+        size_of::<Self>() + self.iter().map(WeightOf::weight_of).sum::<usize>()
+    }
+}
+
+impl<T: WeightOf> WeightOf for Box<T> {
+    fn weight_of(&self) -> usize {
+        (**self).weight_of() + size_of::<Self>()
+    }
+}
+
+impl WeightOf for str {
+    fn weight_of(&self) -> usize {
+        self.len()
+    }
+}
+
+impl_size_of! {
+    // primitives
+    u8, u16, u32, u64, u128, usize,
+    i8, i16, i32, i64, i128, isize,
+    f32, f64, bool, char,
+    // cl-structures
+    Span,
+    // cl-ast
+    Visibility, Mutability, Semi, ModifyKind, BinaryKind, UnaryKind
+}
+
+impl<T> WeightOf for Interned<'_, T> {
+    fn weight_of(&self) -> usize {
+        size_of_val(self) // interned values are opaque to SizeOF
+    }
+}
+
+macro impl_size_of($($T:ty),*$(,)?) {
+    $(impl WeightOf for $T {
+        fn weight_of(&self) -> usize {
+            ::std::mem::size_of_val(self)
+        }
+    })*
+}

compiler/cl-ast/src/ast_visitor.rs

@@ -0,0 +1,12 @@
+//! Contains an [immutable visitor](Visit) and an [owned folder](Fold) trait,
+//! with default implementations across the entire AST
+
+pub mod fold;
+
+pub mod visit;
+pub mod walk;
+
+pub use fold::Fold;
+
+pub use visit::Visit;
+pub use walk::Walk;

compiler/cl-ast/src/ast_visitor/fold.rs

@@ -0,0 +1,595 @@
+//! A folder (implementer of the [Fold] trait) maps ASTs to ASTs
+
+use crate::ast::*;
+use cl_structures::span::Span;
+
+/// Deconstructs the entire AST, and reconstructs it from scratch.
+///
+/// Each method acts as a customization point.
+///
+/// There are a set of default implementations for enums
+/// under the name [`or_fold_`*](or_fold_expr_kind),
+/// provided for ease of use.
+///
+/// For all other nodes, traversal is *explicit*.
+pub trait Fold {
+    fn fold_span(&mut self, span: Span) -> Span {
+        span
+    }
+    fn fold_mutability(&mut self, mutability: Mutability) -> Mutability {
+        mutability
+    }
+    fn fold_visibility(&mut self, visibility: Visibility) -> Visibility {
+        visibility
+    }
+    fn fold_sym(&mut self, ident: Sym) -> Sym {
+        ident
+    }
+    fn fold_literal(&mut self, lit: Literal) -> Literal {
+        or_fold_literal(self, lit)
+    }
+    fn fold_bool(&mut self, b: bool) -> bool {
+        b
+    }
+    fn fold_char(&mut self, c: char) -> char {
+        c
+    }
+    fn fold_int(&mut self, i: u128) -> u128 {
+        i
+    }
+    fn fold_smuggled_float(&mut self, f: u64) -> u64 {
+        f
+    }
+    fn fold_string(&mut self, s: String) -> String {
+        s
+    }
+    fn fold_file(&mut self, f: File) -> File {
+        let File { name, items } = f;
+        File { name, items: items.into_iter().map(|i| self.fold_item(i)).collect() }
+    }
+    fn fold_attrs(&mut self, a: Attrs) -> Attrs {
+        let Attrs { meta } = a;
+        Attrs { meta: meta.into_iter().map(|m| self.fold_meta(m)).collect() }
+    }
+    fn fold_meta(&mut self, m: Meta) -> Meta {
+        let Meta { name, kind } = m;
+        Meta { name: self.fold_sym(name), kind: self.fold_meta_kind(kind) }
+    }
+    fn fold_meta_kind(&mut self, kind: MetaKind) -> MetaKind {
+        or_fold_meta_kind(self, kind)
+    }
+    fn fold_item(&mut self, i: Item) -> Item {
+        let Item { span, attrs, vis, kind } = i;
+        Item {
+            span: self.fold_span(span),
+            attrs: self.fold_attrs(attrs),
+            vis: self.fold_visibility(vis),
+            kind: self.fold_item_kind(kind),
+        }
+    }
+    fn fold_item_kind(&mut self, kind: ItemKind) -> ItemKind {
+        or_fold_item_kind(self, kind)
+    }
+    fn fold_generics(&mut self, gens: Generics) -> Generics {
+        let Generics { vars } = gens;
+        Generics { vars: vars.into_iter().map(|sym| self.fold_sym(sym)).collect() }
+    }
+    fn fold_alias(&mut self, a: Alias) -> Alias {
+        let Alias { name, from } = a;
+        Alias { name: self.fold_sym(name), from: from.map(|from| Box::new(self.fold_ty(*from))) }
+    }
+    fn fold_const(&mut self, c: Const) -> Const {
+        let Const { name, ty, init } = c;
+        Const {
+            name: self.fold_sym(name),
+            ty: Box::new(self.fold_ty(*ty)),
+            init: Box::new(self.fold_expr(*init)),
+        }
+    }
+    fn fold_static(&mut self, s: Static) -> Static {
+        let Static { mutable, name, ty, init } = s;
+        Static {
+            mutable: self.fold_mutability(mutable),
+            name: self.fold_sym(name),
+            ty: Box::new(self.fold_ty(*ty)),
+            init: Box::new(self.fold_expr(*init)),
+        }
+    }
+    fn fold_module(&mut self, m: Module) -> Module {
+        let Module { name, file } = m;
+        Module { name: self.fold_sym(name), file: file.map(|v| self.fold_file(v)) }
+    }
+    fn fold_function(&mut self, f: Function) -> Function {
+        let Function { name, gens, sign, bind, body } = f;
+        Function {
+            name: self.fold_sym(name),
+            gens: self.fold_generics(gens),
+            sign: self.fold_ty_fn(sign),
+            bind: self.fold_pattern(bind),
+            body: body.map(|b| self.fold_expr(b)),
+        }
+    }
+    fn fold_struct(&mut self, s: Struct) -> Struct {
+        let Struct { name, gens, kind } = s;
+        Struct {
+            name: self.fold_sym(name),
+            gens: self.fold_generics(gens),
+            kind: self.fold_struct_kind(kind),
+        }
+    }
+    fn fold_struct_kind(&mut self, kind: StructKind) -> StructKind {
+        match kind {
+            StructKind::Empty => StructKind::Empty,
+            StructKind::Tuple(tys) => {
+                StructKind::Tuple(tys.into_iter().map(|t| self.fold_ty(t)).collect())
+            }
+            StructKind::Struct(mem) => StructKind::Struct(
+                mem.into_iter()
+                    .map(|m| self.fold_struct_member(m))
+                    .collect(),
+            ),
+        }
+    }
+    fn fold_struct_member(&mut self, m: StructMember) -> StructMember {
+        let StructMember { vis, name, ty } = m;
+        StructMember {
+            vis: self.fold_visibility(vis),
+            name: self.fold_sym(name),
+            ty: self.fold_ty(ty),
+        }
+    }
+    fn fold_enum(&mut self, e: Enum) -> Enum {
+        let Enum { name, gens, variants: kind } = e;
+        Enum {
+            name: self.fold_sym(name),
+            gens: self.fold_generics(gens),
+            variants: kind.into_iter().map(|v| self.fold_variant(v)).collect(),
+        }
+    }
+    fn fold_variant(&mut self, v: Variant) -> Variant {
+        let Variant { name, kind, body } = v;
+
+        Variant {
+            name: self.fold_sym(name),
+            kind: self.fold_struct_kind(kind),
+            body: body.map(|e| Box::new(self.fold_expr(*e))),
+        }
+    }
+    fn fold_impl(&mut self, i: Impl) -> Impl {
+        let Impl { gens, target, body } = i;
+        Impl {
+            gens: self.fold_generics(gens),
+            target: self.fold_impl_kind(target),
+            body: self.fold_file(body),
+        }
+    }
+    fn fold_impl_kind(&mut self, kind: ImplKind) -> ImplKind {
+        or_fold_impl_kind(self, kind)
+    }
+    fn fold_use(&mut self, u: Use) -> Use {
+        let Use { absolute, tree } = u;
+        Use { absolute, tree: self.fold_use_tree(tree) }
+    }
+    fn fold_use_tree(&mut self, tree: UseTree) -> UseTree {
+        or_fold_use_tree(self, tree)
+    }
+    fn fold_ty(&mut self, t: Ty) -> Ty {
+        let Ty { span, kind, gens } = t;
+        Ty {
+            span: self.fold_span(span),
+            kind: self.fold_ty_kind(kind),
+            gens: self.fold_generics(gens),
+        }
+    }
+    fn fold_ty_kind(&mut self, kind: TyKind) -> TyKind {
+        or_fold_ty_kind(self, kind)
+    }
+    fn fold_ty_array(&mut self, a: TyArray) -> TyArray {
+        let TyArray { ty, count } = a;
+        TyArray { ty: Box::new(self.fold_ty(*ty)), count }
+    }
+    fn fold_ty_slice(&mut self, s: TySlice) -> TySlice {
+        let TySlice { ty } = s;
+        TySlice { ty: Box::new(self.fold_ty(*ty)) }
+    }
+    fn fold_ty_tuple(&mut self, t: TyTuple) -> TyTuple {
+        let TyTuple { types } = t;
+        TyTuple { types: types.into_iter().map(|kind| self.fold_ty(kind)).collect() }
+    }
+    fn fold_ty_ref(&mut self, t: TyRef) -> TyRef {
+        let TyRef { mutable, count, to } = t;
+        TyRef { mutable: self.fold_mutability(mutable), count, to: Box::new(self.fold_ty(*to)) }
+    }
+    fn fold_ty_ptr(&mut self, t: TyPtr) -> TyPtr {
+        let TyPtr { to } = t;
+        TyPtr { to: Box::new(self.fold_ty(*to)) }
+    }
+    fn fold_ty_fn(&mut self, t: TyFn) -> TyFn {
+        let TyFn { args, rety } = t;
+        TyFn { args: Box::new(self.fold_ty(*args)), rety: Box::new(self.fold_ty(*rety)) }
+    }
+    fn fold_path(&mut self, p: Path) -> Path {
+        let Path { absolute, parts } = p;
+        Path { absolute, parts: parts.into_iter().map(|p| self.fold_path_part(p)).collect() }
+    }
+    fn fold_path_part(&mut self, p: PathPart) -> PathPart {
+        match p {
+            PathPart::SuperKw => PathPart::SuperKw,
+            PathPart::SelfTy => PathPart::SelfTy,
+            PathPart::Ident(i) => PathPart::Ident(self.fold_sym(i)),
+        }
+    }
+    fn fold_stmt(&mut self, s: Stmt) -> Stmt {
+        let Stmt { span, kind, semi } = s;
+        Stmt {
+            span: self.fold_span(span),
+            kind: self.fold_stmt_kind(kind),
+            semi: self.fold_semi(semi),
+        }
+    }
+    fn fold_stmt_kind(&mut self, kind: StmtKind) -> StmtKind {
+        or_fold_stmt_kind(self, kind)
+    }
+    fn fold_semi(&mut self, s: Semi) -> Semi {
+        s
+    }
+    fn fold_expr(&mut self, e: Expr) -> Expr {
+        let Expr { span, kind } = e;
+        Expr { span: self.fold_span(span), kind: self.fold_expr_kind(kind) }
+    }
+    fn fold_expr_kind(&mut self, kind: ExprKind) -> ExprKind {
+        or_fold_expr_kind(self, kind)
+    }
+    fn fold_closure(&mut self, value: Closure) -> Closure {
+        let Closure { arg, body } = value;
+        Closure { arg: Box::new(self.fold_pattern(*arg)), body: Box::new(self.fold_expr(*body)) }
+    }
+    fn fold_let(&mut self, l: Let) -> Let {
+        let Let { mutable, name, ty, init } = l;
+        Let {
+            mutable: self.fold_mutability(mutable),
+            name: self.fold_pattern(name),
+            ty: ty.map(|t| Box::new(self.fold_ty(*t))),
+            init: init.map(|e| Box::new(self.fold_expr(*e))),
+        }
+    }
+
+    fn fold_pattern(&mut self, p: Pattern) -> Pattern {
+        match p {
+            Pattern::Name(sym) => Pattern::Name(self.fold_sym(sym)),
+            Pattern::Path(path) => Pattern::Path(self.fold_path(path)),
+            Pattern::Literal(literal) => Pattern::Literal(self.fold_literal(literal)),
+            Pattern::Rest(Some(name)) => Pattern::Rest(Some(self.fold_pattern(*name).into())),
+            Pattern::Rest(None) => Pattern::Rest(None),
+            Pattern::Ref(mutability, pattern) => Pattern::Ref(
+                self.fold_mutability(mutability),
+                Box::new(self.fold_pattern(*pattern)),
+            ),
+            Pattern::RangeExc(head, tail) => Pattern::RangeInc(
+                Box::new(self.fold_pattern(*head)),
+                Box::new(self.fold_pattern(*tail)),
+            ),
+            Pattern::RangeInc(head, tail) => Pattern::RangeInc(
+                Box::new(self.fold_pattern(*head)),
+                Box::new(self.fold_pattern(*tail)),
+            ),
+            Pattern::Tuple(patterns) => {
+                Pattern::Tuple(patterns.into_iter().map(|p| self.fold_pattern(p)).collect())
+            }
+            Pattern::Array(patterns) => {
+                Pattern::Array(patterns.into_iter().map(|p| self.fold_pattern(p)).collect())
+            }
+            Pattern::Struct(path, items) => Pattern::Struct(
+                self.fold_path(path),
+                items
+                    .into_iter()
+                    .map(|(name, bind)| (name, bind.map(|p| self.fold_pattern(p))))
+                    .collect(),
+            ),
+            Pattern::TupleStruct(path, items) => Pattern::TupleStruct(
+                self.fold_path(path),
+                items
+                    .into_iter()
+                    .map(|bind| self.fold_pattern(bind))
+                    .collect(),
+            ),
+        }
+    }
+
+    fn fold_match(&mut self, m: Match) -> Match {
+        let Match { scrutinee, arms } = m;
+        Match {
+            scrutinee: self.fold_expr(*scrutinee).into(),
+            arms: arms
+                .into_iter()
+                .map(|arm| self.fold_match_arm(arm))
+                .collect(),
+        }
+    }
+
+    fn fold_match_arm(&mut self, a: MatchArm) -> MatchArm {
+        let MatchArm(pat, expr) = a;
+        MatchArm(self.fold_pattern(pat), self.fold_expr(expr))
+    }
+
+    fn fold_assign(&mut self, a: Assign) -> Assign {
+        let Assign { parts } = a;
+        let (head, tail) = *parts;
+        Assign { parts: Box::new((self.fold_expr(head), self.fold_expr(tail))) }
+    }
+    fn fold_modify(&mut self, m: Modify) -> Modify {
+        let Modify { kind, parts } = m;
+        let (head, tail) = *parts;
+        Modify {
+            kind: self.fold_modify_kind(kind),
+            parts: Box::new((self.fold_expr(head), self.fold_expr(tail))),
+        }
+    }
+    fn fold_modify_kind(&mut self, kind: ModifyKind) -> ModifyKind {
+        kind
+    }
+    fn fold_binary(&mut self, b: Binary) -> Binary {
+        let Binary { kind, parts } = b;
+        let (head, tail) = *parts;
+        Binary {
+            kind: self.fold_binary_kind(kind),
+            parts: Box::new((self.fold_expr(head), self.fold_expr(tail))),
+        }
+    }
+    fn fold_binary_kind(&mut self, kind: BinaryKind) -> BinaryKind {
+        kind
+    }
+    fn fold_unary(&mut self, u: Unary) -> Unary {
+        let Unary { kind, tail } = u;
+        Unary { kind: self.fold_unary_kind(kind), tail: Box::new(self.fold_expr(*tail)) }
+    }
+    fn fold_unary_kind(&mut self, kind: UnaryKind) -> UnaryKind {
+        kind
+    }
+    fn fold_cast(&mut self, cast: Cast) -> Cast {
+        let Cast { head, ty } = cast;
+        Cast { head: Box::new(self.fold_expr(*head)), ty: self.fold_ty(ty) }
+    }
+    fn fold_member(&mut self, m: Member) -> Member {
+        let Member { head, kind } = m;
+        Member { head: Box::new(self.fold_expr(*head)), kind: self.fold_member_kind(kind) }
+    }
+    fn fold_member_kind(&mut self, kind: MemberKind) -> MemberKind {
+        or_fold_member_kind(self, kind)
+    }
+    fn fold_index(&mut self, i: Index) -> Index {
+        let Index { head, indices } = i;
+        Index {
+            head: Box::new(self.fold_expr(*head)),
+            indices: indices.into_iter().map(|e| self.fold_expr(e)).collect(),
+        }
+    }
+
+    fn fold_structor(&mut self, s: Structor) -> Structor {
+        let Structor { to, init } = s;
+        Structor {
+            to: self.fold_path(to),
+            init: init.into_iter().map(|f| self.fold_fielder(f)).collect(),
+        }
+    }
+
+    fn fold_fielder(&mut self, f: Fielder) -> Fielder {
+        let Fielder { name, init } = f;
+        Fielder { name: self.fold_sym(name), init: init.map(|e| Box::new(self.fold_expr(*e))) }
+    }
+    fn fold_array(&mut self, a: Array) -> Array {
+        let Array { values } = a;
+        Array { values: values.into_iter().map(|e| self.fold_expr(e)).collect() }
+    }
+    fn fold_array_rep(&mut self, a: ArrayRep) -> ArrayRep {
+        let ArrayRep { value, repeat } = a;
+        ArrayRep { value: Box::new(self.fold_expr(*value)), repeat }
+    }
+    fn fold_addrof(&mut self, a: AddrOf) -> AddrOf {
+        let AddrOf { mutable, expr } = a;
+        AddrOf { mutable: self.fold_mutability(mutable), expr: Box::new(self.fold_expr(*expr)) }
+    }
+    fn fold_block(&mut self, b: Block) -> Block {
+        let Block { stmts } = b;
+        Block { stmts: stmts.into_iter().map(|s| self.fold_stmt(s)).collect() }
+    }
+    fn fold_group(&mut self, g: Group) -> Group {
+        let Group { expr } = g;
+        Group { expr: Box::new(self.fold_expr(*expr)) }
+    }
+    fn fold_tuple(&mut self, t: Tuple) -> Tuple {
+        let Tuple { exprs } = t;
+        Tuple { exprs: exprs.into_iter().map(|e| self.fold_expr(e)).collect() }
+    }
+    fn fold_while(&mut self, w: While) -> While {
+        let While { cond, pass, fail } = w;
+        While {
+            cond: Box::new(self.fold_expr(*cond)),
+            pass: Box::new(self.fold_block(*pass)),
+            fail: self.fold_else(fail),
+        }
+    }
+    fn fold_if(&mut self, i: If) -> If {
+        let If { cond, pass, fail } = i;
+        If {
+            cond: Box::new(self.fold_expr(*cond)),
+            pass: Box::new(self.fold_block(*pass)),
+            fail: self.fold_else(fail),
+        }
+    }
+    fn fold_for(&mut self, f: For) -> For {
+        let For { bind, cond, pass, fail } = f;
+        For {
+            bind: self.fold_pattern(bind),
+            cond: Box::new(self.fold_expr(*cond)),
+            pass: Box::new(self.fold_block(*pass)),
+            fail: self.fold_else(fail),
+        }
+    }
+    fn fold_else(&mut self, e: Else) -> Else {
+        let Else { body } = e;
+        Else { body: body.map(|e| Box::new(self.fold_expr(*e))) }
+    }
+    fn fold_break(&mut self, b: Break) -> Break {
+        let Break { body } = b;
+        Break { body: body.map(|e| Box::new(self.fold_expr(*e))) }
+    }
+    fn fold_return(&mut self, r: Return) -> Return {
+        let Return { body } = r;
+        Return { body: body.map(|e| Box::new(self.fold_expr(*e))) }
+    }
+}
+
+#[inline]
+/// Folds a [Literal] in the default way
+pub fn or_fold_literal<F: Fold + ?Sized>(folder: &mut F, lit: Literal) -> Literal {
+    match lit {
+        Literal::Bool(b) => Literal::Bool(folder.fold_bool(b)),
+        Literal::Char(c) => Literal::Char(folder.fold_char(c)),
+        Literal::Int(i) => Literal::Int(folder.fold_int(i)),
+        Literal::Float(f) => Literal::Float(folder.fold_smuggled_float(f)),
+        Literal::String(s) => Literal::String(folder.fold_string(s)),
+    }
+}
+
+#[inline]
+/// Folds a [MetaKind] in the default way
+pub fn or_fold_meta_kind<F: Fold + ?Sized>(folder: &mut F, kind: MetaKind) -> MetaKind {
+    match kind {
+        MetaKind::Plain => MetaKind::Plain,
+        MetaKind::Equals(l) => MetaKind::Equals(folder.fold_literal(l)),
+        MetaKind::Func(lits) => {
+            MetaKind::Func(lits.into_iter().map(|l| folder.fold_literal(l)).collect())
+        }
+    }
+}
+
+#[inline]
+/// Folds an [ItemKind] in the default way
+pub fn or_fold_item_kind<F: Fold + ?Sized>(folder: &mut F, kind: ItemKind) -> ItemKind {
+    match kind {
+        ItemKind::Module(m) => ItemKind::Module(folder.fold_module(m)),
+        ItemKind::Alias(a) => ItemKind::Alias(folder.fold_alias(a)),
+        ItemKind::Enum(e) => ItemKind::Enum(folder.fold_enum(e)),
+        ItemKind::Struct(s) => ItemKind::Struct(folder.fold_struct(s)),
+        ItemKind::Const(c) => ItemKind::Const(folder.fold_const(c)),
+        ItemKind::Static(s) => ItemKind::Static(folder.fold_static(s)),
+        ItemKind::Function(f) => ItemKind::Function(folder.fold_function(f)),
+        ItemKind::Impl(i) => ItemKind::Impl(folder.fold_impl(i)),
+        ItemKind::Use(u) => ItemKind::Use(folder.fold_use(u)),
+    }
+}
+
+#[inline]
+/// Folds a [StructKind] in the default way
+pub fn or_fold_struct_kind<F: Fold + ?Sized>(folder: &mut F, kind: StructKind) -> StructKind {
+    match kind {
+        StructKind::Empty => StructKind::Empty,
+        StructKind::Tuple(tys) => {
+            StructKind::Tuple(tys.into_iter().map(|t| folder.fold_ty(t)).collect())
+        }
+        StructKind::Struct(mem) => StructKind::Struct(
+            mem.into_iter()
+                .map(|m| folder.fold_struct_member(m))
+                .collect(),
+        ),
+    }
+}
+
+#[inline]
+/// Folds an [ImplKind] in the default way
+pub fn or_fold_impl_kind<F: Fold + ?Sized>(folder: &mut F, kind: ImplKind) -> ImplKind {
+    match kind {
+        ImplKind::Type(t) => ImplKind::Type(folder.fold_ty(t)),
+        ImplKind::Trait { impl_trait, for_type } => ImplKind::Trait {
+            impl_trait: folder.fold_path(impl_trait),
+            for_type: Box::new(folder.fold_ty(*for_type)),
+        },
+    }
+}
+
+#[inline]
+pub fn or_fold_use_tree<F: Fold + ?Sized>(folder: &mut F, tree: UseTree) -> UseTree {
+    match tree {
+        UseTree::Tree(tree) => UseTree::Tree(
+            tree.into_iter()
+                .map(|tree| folder.fold_use_tree(tree))
+                .collect(),
+        ),
+        UseTree::Path(path, rest) => UseTree::Path(
+            folder.fold_path_part(path),
+            Box::new(folder.fold_use_tree(*rest)),
+        ),
+        UseTree::Alias(path, name) => UseTree::Alias(folder.fold_sym(path), folder.fold_sym(name)),
+        UseTree::Name(name) => UseTree::Name(folder.fold_sym(name)),
+        UseTree::Glob => UseTree::Glob,
+    }
+}
+
+#[inline]
+/// Folds a [TyKind] in the default way
+pub fn or_fold_ty_kind<F: Fold + ?Sized>(folder: &mut F, kind: TyKind) -> TyKind {
+    match kind {
+        TyKind::Never => TyKind::Never,
+        TyKind::Infer => TyKind::Infer,
+        TyKind::Path(p) => TyKind::Path(folder.fold_path(p)),
+        TyKind::Array(a) => TyKind::Array(folder.fold_ty_array(a)),
+        TyKind::Slice(s) => TyKind::Slice(folder.fold_ty_slice(s)),
+        TyKind::Tuple(t) => TyKind::Tuple(folder.fold_ty_tuple(t)),
+        TyKind::Ref(t) => TyKind::Ref(folder.fold_ty_ref(t)),
+        TyKind::Ptr(t) => TyKind::Ptr(folder.fold_ty_ptr(t)),
+        TyKind::Fn(t) => TyKind::Fn(folder.fold_ty_fn(t)),
+    }
+}
+
+#[inline]
+/// Folds a [StmtKind] in the default way
+pub fn or_fold_stmt_kind<F: Fold + ?Sized>(folder: &mut F, kind: StmtKind) -> StmtKind {
+    match kind {
+        StmtKind::Empty => StmtKind::Empty,
+        StmtKind::Item(i) => StmtKind::Item(Box::new(folder.fold_item(*i))),
+        StmtKind::Expr(e) => StmtKind::Expr(Box::new(folder.fold_expr(*e))),
+    }
+}
+#[inline]
+/// Folds an [ExprKind] in the default way
+pub fn or_fold_expr_kind<F: Fold + ?Sized>(folder: &mut F, kind: ExprKind) -> ExprKind {
+    match kind {
+        ExprKind::Empty => ExprKind::Empty,
+        ExprKind::Closure(c) => ExprKind::Closure(folder.fold_closure(c)),
+        ExprKind::Quote(q) => ExprKind::Quote(q), // quoted expressions are left unmodified
+        ExprKind::Let(l) => ExprKind::Let(folder.fold_let(l)),
+        ExprKind::Match(m) => ExprKind::Match(folder.fold_match(m)),
+        ExprKind::Assign(a) => ExprKind::Assign(folder.fold_assign(a)),
+        ExprKind::Modify(m) => ExprKind::Modify(folder.fold_modify(m)),
+        ExprKind::Binary(b) => ExprKind::Binary(folder.fold_binary(b)),
+        ExprKind::Unary(u) => ExprKind::Unary(folder.fold_unary(u)),
+        ExprKind::Cast(c) => ExprKind::Cast(folder.fold_cast(c)),
+        ExprKind::Member(m) => ExprKind::Member(folder.fold_member(m)),
+        ExprKind::Index(i) => ExprKind::Index(folder.fold_index(i)),
+        ExprKind::Structor(s) => ExprKind::Structor(folder.fold_structor(s)),
+        ExprKind::Path(p) => ExprKind::Path(folder.fold_path(p)),
+        ExprKind::Literal(l) => ExprKind::Literal(folder.fold_literal(l)),
+        ExprKind::Array(a) => ExprKind::Array(folder.fold_array(a)),
+        ExprKind::ArrayRep(a) => ExprKind::ArrayRep(folder.fold_array_rep(a)),
+        ExprKind::AddrOf(a) => ExprKind::AddrOf(folder.fold_addrof(a)),
+        ExprKind::Block(b) => ExprKind::Block(folder.fold_block(b)),
+        ExprKind::Group(g) => ExprKind::Group(folder.fold_group(g)),
+        ExprKind::Tuple(t) => ExprKind::Tuple(folder.fold_tuple(t)),
+        ExprKind::While(w) => ExprKind::While(folder.fold_while(w)),
+        ExprKind::If(i) => ExprKind::If(folder.fold_if(i)),
+        ExprKind::For(f) => ExprKind::For(folder.fold_for(f)),
+        ExprKind::Break(b) => ExprKind::Break(folder.fold_break(b)),
+        ExprKind::Return(r) => ExprKind::Return(folder.fold_return(r)),
+        ExprKind::Continue => ExprKind::Continue,
+    }
+}
+pub fn or_fold_member_kind<F: Fold + ?Sized>(folder: &mut F, kind: MemberKind) -> MemberKind {
+    match kind {
+        MemberKind::Call(name, args) => {
+            MemberKind::Call(folder.fold_sym(name), folder.fold_tuple(args))
+        }
+        MemberKind::Struct(name) => MemberKind::Struct(folder.fold_sym(name)),
+        MemberKind::Tuple(name) => MemberKind::Tuple(folder.fold_literal(name)),
+    }
+}

compiler/cl-ast/src/ast_visitor/visit.rs

@@ -0,0 +1,260 @@
+//! A [visitor](Visit) (implementer of the [Visit] trait) walks the immutable AST, mutating itself.
+
+use crate::ast::*;
+use cl_structures::span::Span;
+
+use super::walk::Walk;
+
+/// Immutably walks the entire AST
+///
+/// Each method acts as a customization point.
+pub trait Visit<'a>: Sized {
+    /// Visits a [Walker](Walk)
+    #[inline]
+    fn visit<W: Walk>(&mut self, walker: &'a W) -> &mut Self {
+        walker.visit_in(self);
+        self
+    }
+    /// Visits the children of a [Walker](Walk)
+    fn visit_children<W: Walk>(&mut self, walker: &'a W) {
+        walker.children(self)
+    }
+
+    fn visit_span(&mut self, value: &'a Span) {
+        value.children(self)
+    }
+    fn visit_mutability(&mut self, value: &'a Mutability) {
+        value.children(self)
+    }
+    fn visit_visibility(&mut self, value: &'a Visibility) {
+        value.children(self)
+    }
+    fn visit_sym(&mut self, value: &'a Sym) {
+        value.children(self)
+    }
+    fn visit_literal(&mut self, value: &'a Literal) {
+        value.children(self)
+    }
+    fn visit_bool(&mut self, value: &'a bool) {
+        value.children(self)
+    }
+    fn visit_char(&mut self, value: &'a char) {
+        value.children(self)
+    }
+    fn visit_int(&mut self, value: &'a u128) {
+        value.children(self)
+    }
+    fn visit_smuggled_float(&mut self, value: &'a u64) {
+        value.children(self)
+    }
+    fn visit_string(&mut self, value: &'a str) {
+        value.children(self)
+    }
+    fn visit_file(&mut self, value: &'a File) {
+        value.children(self)
+    }
+    fn visit_attrs(&mut self, value: &'a Attrs) {
+        value.children(self)
+    }
+    fn visit_meta(&mut self, value: &'a Meta) {
+        value.children(self)
+    }
+    fn visit_meta_kind(&mut self, value: &'a MetaKind) {
+        value.children(self)
+    }
+    fn visit_item(&mut self, value: &'a Item) {
+        value.children(self)
+    }
+    fn visit_item_kind(&mut self, value: &'a ItemKind) {
+        value.children(self)
+    }
+    fn visit_generics(&mut self, value: &'a Generics) {
+        value.children(self)
+    }
+    fn visit_alias(&mut self, value: &'a Alias) {
+        value.children(self)
+    }
+    fn visit_const(&mut self, value: &'a Const) {
+        value.children(self)
+    }
+    fn visit_static(&mut self, value: &'a Static) {
+        value.children(self)
+    }
+    fn visit_module(&mut self, value: &'a Module) {
+        value.children(self)
+    }
+    fn visit_function(&mut self, value: &'a Function) {
+        value.children(self)
+    }
+    fn visit_struct(&mut self, value: &'a Struct) {
+        value.children(self)
+    }
+    fn visit_struct_kind(&mut self, value: &'a StructKind) {
+        value.children(self)
+    }
+    fn visit_struct_member(&mut self, value: &'a StructMember) {
+        value.children(self)
+    }
+    fn visit_enum(&mut self, value: &'a Enum) {
+        value.children(self)
+    }
+    fn visit_variant(&mut self, value: &'a Variant) {
+        value.children(self)
+    }
+    fn visit_impl(&mut self, value: &'a Impl) {
+        value.children(self)
+    }
+    fn visit_impl_kind(&mut self, value: &'a ImplKind) {
+        value.children(self)
+    }
+    fn visit_use(&mut self, value: &'a Use) {
+        value.children(self)
+    }
+    fn visit_use_tree(&mut self, value: &'a UseTree) {
+        value.children(self)
+    }
+    fn visit_ty(&mut self, value: &'a Ty) {
+        value.children(self)
+    }
+    fn visit_ty_kind(&mut self, value: &'a TyKind) {
+        value.children(self)
+    }
+    fn visit_ty_array(&mut self, value: &'a TyArray) {
+        value.children(self)
+    }
+    fn visit_ty_slice(&mut self, value: &'a TySlice) {
+        value.children(self)
+    }
+    fn visit_ty_tuple(&mut self, value: &'a TyTuple) {
+        value.children(self)
+    }
+    fn visit_ty_ref(&mut self, value: &'a TyRef) {
+        value.children(self)
+    }
+    fn visit_ty_ptr(&mut self, value: &'a TyPtr) {
+        value.children(self)
+    }
+    fn visit_ty_fn(&mut self, value: &'a TyFn) {
+        value.children(self)
+    }
+    fn visit_path(&mut self, value: &'a Path) {
+        value.children(self)
+    }
+    fn visit_path_part(&mut self, value: &'a PathPart) {
+        value.children(self)
+    }
+    fn visit_stmt(&mut self, value: &'a Stmt) {
+        value.children(self)
+    }
+    fn visit_stmt_kind(&mut self, value: &'a StmtKind) {
+        value.children(self)
+    }
+    fn visit_semi(&mut self, value: &'a Semi) {
+        value.children(self)
+    }
+    fn visit_expr(&mut self, value: &'a Expr) {
+        value.children(self)
+    }
+    fn visit_expr_kind(&mut self, value: &'a ExprKind) {
+        value.children(self)
+    }
+    fn visit_closure(&mut self, value: &'a Closure) {
+        value.children(self)
+    }
+    fn visit_quote(&mut self, value: &'a Quote) {
+        value.children(self)
+    }
+    fn visit_let(&mut self, value: &'a Let) {
+        value.children(self)
+    }
+
+    fn visit_pattern(&mut self, value: &'a Pattern) {
+        value.children(self)
+    }
+
+    fn visit_match(&mut self, value: &'a Match) {
+        value.children(self)
+    }
+
+    fn visit_match_arm(&mut self, value: &'a MatchArm) {
+        value.children(self)
+    }
+
+    fn visit_assign(&mut self, value: &'a Assign) {
+        value.children(self)
+    }
+    fn visit_modify(&mut self, value: &'a Modify) {
+        value.children(self)
+    }
+    fn visit_modify_kind(&mut self, value: &'a ModifyKind) {
+        value.children(self)
+    }
+    fn visit_binary(&mut self, value: &'a Binary) {
+        value.children(self)
+    }
+    fn visit_binary_kind(&mut self, value: &'a BinaryKind) {
+        value.children(self)
+    }
+    fn visit_unary(&mut self, value: &'a Unary) {
+        value.children(self)
+    }
+    fn visit_unary_kind(&mut self, value: &'a UnaryKind) {
+        value.children(self)
+    }
+
+    fn visit_cast(&mut self, value: &'a Cast) {
+        value.children(self)
+    }
+    fn visit_member(&mut self, value: &'a Member) {
+        value.children(self)
+    }
+    fn visit_member_kind(&mut self, value: &'a MemberKind) {
+        value.children(self)
+    }
+    fn visit_index(&mut self, value: &'a Index) {
+        value.children(self)
+    }
+    fn visit_structor(&mut self, value: &'a Structor) {
+        value.children(self)
+    }
+    fn visit_fielder(&mut self, value: &'a Fielder) {
+        value.children(self)
+    }
+    fn visit_array(&mut self, value: &'a Array) {
+        value.children(self)
+    }
+    fn visit_array_rep(&mut self, value: &'a ArrayRep) {
+        value.children(self)
+    }
+    fn visit_addrof(&mut self, value: &'a AddrOf) {
+        value.children(self)
+    }
+    fn visit_block(&mut self, value: &'a Block) {
+        value.children(self)
+    }
+    fn visit_group(&mut self, value: &'a Group) {
+        value.children(self)
+    }
+    fn visit_tuple(&mut self, value: &'a Tuple) {
+        value.children(self)
+    }
+    fn visit_while(&mut self, value: &'a While) {
+        value.children(self)
+    }
+    fn visit_if(&mut self, value: &'a If) {
+        value.children(self)
+    }
+    fn visit_for(&mut self, value: &'a For) {
+        value.children(self)
+    }
+    fn visit_else(&mut self, value: &'a Else) {
+        value.children(self)
+    }
+    fn visit_break(&mut self, value: &'a Break) {
+        value.children(self)
+    }
+    fn visit_return(&mut self, value: &'a Return) {
+        value.children(self)
+    }
+    fn visit_continue(&mut self) {}
+}

compiler/cl-ast/src/ast_visitor/walk.rs

@@ -0,0 +1,963 @@
+//! Accepts an AST Visitor. Walks the AST, calling the visitor on each step.
+
+use super::visit::Visit;
+use crate::ast::*;
+use cl_structures::span::Span;
+
+/// Helps a [Visitor](Visit) walk through `Self`.
+pub trait Walk {
+    /// Calls the respective `visit_*` function in V
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V);
+
+    #[allow(unused)]
+    /// Walks the children of self, visiting them in V
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {}
+}
+
+impl Walk for Span {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_span(self);
+    }
+}
+impl Walk for Sym {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_sym(self);
+    }
+}
+impl Walk for Mutability {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_mutability(self);
+    }
+}
+impl Walk for Visibility {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_visibility(self);
+    }
+}
+impl Walk for bool {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_bool(self);
+    }
+}
+impl Walk for char {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_char(self);
+    }
+}
+impl Walk for u128 {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_int(self);
+    }
+}
+impl Walk for u64 {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_smuggled_float(self);
+    }
+}
+impl Walk for str {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_string(self);
+    }
+}
+impl Walk for Literal {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_literal(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        match self {
+            Literal::Bool(value) => value.children(v),
+            Literal::Char(value) => value.children(v),
+            Literal::Int(value) => value.children(v),
+            Literal::Float(value) => value.children(v),
+            Literal::String(value) => value.children(v),
+        };
+    }
+}
+impl Walk for File {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_file(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let File { name: _, items } = self;
+        items.iter().for_each(|i| v.visit_item(i));
+    }
+}
+impl Walk for Attrs {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_attrs(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Attrs { meta } = self;
+        meta.children(v);
+    }
+}
+impl Walk for Meta {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_meta(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Meta { name, kind } = self;
+        name.visit_in(v);
+        kind.visit_in(v);
+    }
+}
+impl Walk for MetaKind {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_meta_kind(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        match self {
+            MetaKind::Plain => {}
+            MetaKind::Equals(lit) => lit.visit_in(v),
+            MetaKind::Func(lits) => lits.visit_in(v),
+        }
+    }
+}
+impl Walk for Item {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_item(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Item { span, attrs, vis, kind } = self;
+        span.visit_in(v);
+        attrs.visit_in(v);
+        vis.visit_in(v);
+        kind.visit_in(v);
+    }
+}
+impl Walk for ItemKind {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_item_kind(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        match self {
+            ItemKind::Module(value) => value.visit_in(v),
+            ItemKind::Alias(value) => value.visit_in(v),
+            ItemKind::Enum(value) => value.visit_in(v),
+            ItemKind::Struct(value) => value.visit_in(v),
+            ItemKind::Const(value) => value.visit_in(v),
+            ItemKind::Static(value) => value.visit_in(v),
+            ItemKind::Function(value) => value.visit_in(v),
+            ItemKind::Impl(value) => value.visit_in(v),
+            ItemKind::Use(value) => value.visit_in(v),
+        }
+    }
+}
+impl Walk for Generics {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_generics(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Self { vars } = self;
+        vars.visit_in(v);
+    }
+}
+impl Walk for Module {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_module(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Module { name, file } = self;
+        name.visit_in(v);
+        file.visit_in(v);
+    }
+}
+impl Walk for Alias {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_alias(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Alias { name, from } = self;
+        name.visit_in(v);
+        from.visit_in(v);
+    }
+}
+impl Walk for Const {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_const(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Const { name, ty, init } = self;
+        name.visit_in(v);
+        ty.visit_in(v);
+        init.visit_in(v);
+    }
+}
+impl Walk for Static {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_static(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Static { mutable, name, ty, init } = self;
+        mutable.visit_in(v);
+        name.visit_in(v);
+        ty.visit_in(v);
+        init.visit_in(v);
+    }
+}
+impl Walk for Function {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_function(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Function { name, gens, sign, bind, body } = self;
+        name.visit_in(v);
+        gens.visit_in(v);
+        sign.visit_in(v);
+        bind.visit_in(v);
+        body.visit_in(v);
+    }
+}
+impl Walk for Struct {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_struct(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Struct { name, gens, kind } = self;
+        name.visit_in(v);
+        gens.visit_in(v);
+        kind.visit_in(v);
+    }
+}
+impl Walk for StructKind {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_struct_kind(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        match self {
+            StructKind::Empty => {}
+            StructKind::Tuple(tys) => tys.visit_in(v),
+            StructKind::Struct(ms) => ms.visit_in(v),
+        }
+    }
+}
+impl Walk for StructMember {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_struct_member(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let StructMember { vis, name, ty } = self;
+        vis.visit_in(v);
+        name.visit_in(v);
+        ty.visit_in(v);
+    }
+}
+impl Walk for Enum {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_enum(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Enum { name, gens, variants } = self;
+        name.visit_in(v);
+        gens.visit_in(v);
+        variants.visit_in(v);
+    }
+}
+impl Walk for Variant {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_variant(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Variant { name, kind, body } = self;
+        name.visit_in(v);
+        kind.visit_in(v);
+        body.visit_in(v);
+    }
+}
+impl Walk for Impl {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_impl(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Impl { gens, target, body } = self;
+        gens.visit_in(v);
+        target.visit_in(v);
+        body.visit_in(v);
+    }
+}
+impl Walk for ImplKind {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_impl_kind(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        match self {
+            ImplKind::Type(t) => t.visit_in(v),
+            ImplKind::Trait { impl_trait, for_type } => {
+                impl_trait.visit_in(v);
+                for_type.visit_in(v);
+            }
+        }
+    }
+}
+impl Walk for Use {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_use(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Use { absolute: _, tree } = self;
+        tree.visit_in(v);
+    }
+}
+impl Walk for UseTree {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_use_tree(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        match self {
+            UseTree::Tree(tree) => tree.iter().for_each(|t| t.visit_in(v)),
+            UseTree::Path(part, tree) => {
+                part.visit_in(v);
+                tree.visit_in(v);
+            }
+            UseTree::Alias(from, to) => {
+                from.visit_in(v);
+                to.visit_in(v);
+            }
+            UseTree::Name(name) => name.visit_in(v),
+            UseTree::Glob => {}
+        }
+    }
+}
+impl Walk for Ty {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_ty(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Ty { span, kind, gens } = self;
+        span.visit_in(v);
+        kind.visit_in(v);
+        gens.visit_in(v);
+    }
+}
+impl Walk for TyKind {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_ty_kind(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        match self {
+            TyKind::Never => {}
+            TyKind::Infer => {}
+            TyKind::Path(value) => value.visit_in(v),
+            TyKind::Array(value) => value.visit_in(v),
+            TyKind::Slice(value) => value.visit_in(v),
+            TyKind::Tuple(value) => value.visit_in(v),
+            TyKind::Ref(value) => value.visit_in(v),
+            TyKind::Ptr(value) => value.visit_in(v),
+            TyKind::Fn(value) => value.visit_in(v),
+        }
+    }
+}
+impl Walk for TyArray {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_ty_array(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let TyArray { ty, count: _ } = self;
+        ty.visit_in(v);
+        // count.walk(v); // not available
+    }
+}
+impl Walk for TySlice {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_ty_slice(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let TySlice { ty } = self;
+        ty.visit_in(v);
+    }
+}
+impl Walk for TyTuple {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_ty_tuple(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let TyTuple { types } = self;
+        types.visit_in(v);
+    }
+}
+impl Walk for TyRef {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_ty_ref(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let TyRef { mutable, count: _, to } = self;
+        mutable.children(v);
+        to.children(v);
+    }
+}
+impl Walk for TyPtr {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_ty_ptr(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let TyPtr { to } = self;
+        to.children(v);
+    }
+}
+impl Walk for TyFn {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_ty_fn(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let TyFn { args, rety } = self;
+        args.visit_in(v);
+        rety.visit_in(v);
+    }
+}
+impl Walk for Path {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_path(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Path { absolute: _, parts } = self;
+        parts.visit_in(v);
+    }
+}
+impl Walk for PathPart {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_path_part(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        match self {
+            PathPart::SuperKw => {}
+            PathPart::SelfTy => {}
+            PathPart::Ident(sym) => sym.visit_in(v),
+        }
+    }
+}
+impl Walk for Stmt {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_stmt(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Stmt { span, kind, semi } = self;
+        span.visit_in(v);
+        kind.visit_in(v);
+        semi.visit_in(v);
+    }
+}
+impl Walk for StmtKind {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_stmt_kind(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        match self {
+            StmtKind::Empty => {}
+            StmtKind::Item(value) => value.visit_in(v),
+            StmtKind::Expr(value) => value.visit_in(v),
+        }
+    }
+}
+impl Walk for Semi {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_semi(self);
+    }
+}
+impl Walk for Expr {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_expr(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Expr { span, kind } = self;
+        span.visit_in(v);
+        kind.visit_in(v);
+    }
+}
+impl Walk for ExprKind {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_expr_kind(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        match self {
+            ExprKind::Empty => {}
+            ExprKind::Closure(value) => value.visit_in(v),
+            ExprKind::Tuple(value) => value.visit_in(v),
+            ExprKind::Structor(value) => value.visit_in(v),
+            ExprKind::Array(value) => value.visit_in(v),
+            ExprKind::ArrayRep(value) => value.visit_in(v),
+            ExprKind::AddrOf(value) => value.visit_in(v),
+            ExprKind::Quote(value) => value.visit_in(v),
+            ExprKind::Literal(value) => value.visit_in(v),
+            ExprKind::Group(value) => value.visit_in(v),
+            ExprKind::Block(value) => value.visit_in(v),
+            ExprKind::Assign(value) => value.visit_in(v),
+            ExprKind::Modify(value) => value.visit_in(v),
+            ExprKind::Binary(value) => value.visit_in(v),
+            ExprKind::Unary(value) => value.visit_in(v),
+            ExprKind::Member(value) => value.visit_in(v),
+            ExprKind::Index(value) => value.visit_in(v),
+            ExprKind::Cast(value) => value.visit_in(v),
+            ExprKind::Path(value) => value.visit_in(v),
+            ExprKind::Let(value) => value.visit_in(v),
+            ExprKind::Match(value) => value.visit_in(v),
+            ExprKind::While(value) => value.visit_in(v),
+            ExprKind::If(value) => value.visit_in(v),
+            ExprKind::For(value) => value.visit_in(v),
+            ExprKind::Break(value) => value.visit_in(v),
+            ExprKind::Return(value) => value.visit_in(v),
+            ExprKind::Continue => v.visit_continue(),
+        }
+    }
+}
+
+impl Walk for Closure {
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_closure(self);
+    }
+
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Self { arg, body } = self;
+        v.visit_pattern(arg);
+        v.visit_expr(body);
+    }
+}
+
+impl Walk for Tuple {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_tuple(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Tuple { exprs } = self;
+        exprs.visit_in(v);
+    }
+}
+impl Walk for Structor {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_structor(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Structor { to, init } = self;
+        to.visit_in(v);
+        init.visit_in(v);
+    }
+}
+impl Walk for Fielder {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_fielder(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Fielder { name, init } = self;
+        name.visit_in(v);
+        init.visit_in(v);
+    }
+}
+impl Walk for Array {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_array(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Array { values } = self;
+        values.visit_in(v);
+    }
+}
+impl Walk for ArrayRep {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_array_rep(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let ArrayRep { value, repeat: _ } = self;
+        value.visit_in(v);
+        // repeat.visit_in(v) // TODO
+    }
+}
+impl Walk for AddrOf {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_addrof(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let AddrOf { mutable, expr } = self;
+        mutable.visit_in(v);
+        expr.visit_in(v);
+    }
+}
+impl Walk for Cast {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_cast(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Cast { head, ty } = self;
+        head.visit_in(v);
+        ty.visit_in(v);
+    }
+}
+impl Walk for Quote {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_quote(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Quote { quote } = self;
+        quote.visit_in(v);
+    }
+}
+impl Walk for Group {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_group(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Group { expr } = self;
+        expr.visit_in(v);
+    }
+}
+impl Walk for Block {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_block(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Block { stmts } = self;
+        stmts.visit_in(v);
+    }
+}
+impl Walk for Assign {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_assign(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Assign { parts } = self;
+        parts.visit_in(v);
+    }
+}
+impl Walk for Modify {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_modify(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Modify { kind, parts } = self;
+        kind.visit_in(v);
+        parts.visit_in(v);
+    }
+}
+impl Walk for ModifyKind {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_modify_kind(self);
+    }
+}
+impl Walk for Binary {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_binary(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Binary { kind, parts } = self;
+        kind.visit_in(v);
+        parts.visit_in(v);
+    }
+}
+impl Walk for BinaryKind {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_binary_kind(self);
+    }
+}
+impl Walk for Unary {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_unary(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Unary { kind, tail } = self;
+        kind.visit_in(v);
+        tail.visit_in(v);
+    }
+}
+impl Walk for UnaryKind {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_unary_kind(self);
+    }
+}
+impl Walk for Member {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_member(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Member { head, kind } = self;
+        head.visit_in(v);
+        kind.visit_in(v);
+    }
+}
+impl Walk for MemberKind {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_member_kind(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        match self {
+            MemberKind::Call(sym, tuple) => {
+                sym.visit_in(v);
+                tuple.visit_in(v);
+            }
+            MemberKind::Struct(sym) => sym.visit_in(v),
+            MemberKind::Tuple(literal) => literal.visit_in(v),
+        }
+    }
+}
+impl Walk for Index {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_index(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Index { head, indices } = self;
+        head.visit_in(v);
+        indices.visit_in(v);
+    }
+}
+impl Walk for Let {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_let(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Let { mutable, name, ty, init } = self;
+        mutable.visit_in(v);
+        name.visit_in(v);
+        ty.visit_in(v);
+        init.visit_in(v);
+    }
+}
+impl Walk for Match {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_match(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Match { scrutinee, arms } = self;
+        scrutinee.visit_in(v);
+        arms.visit_in(v);
+    }
+}
+impl Walk for MatchArm {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_match_arm(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let MatchArm(pat, expr) = self;
+        pat.visit_in(v);
+        expr.visit_in(v);
+    }
+}
+impl Walk for Pattern {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_pattern(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        match self {
+            Pattern::Name(sym) => sym.visit_in(v),
+            Pattern::Path(path) => path.visit_in(v),
+            Pattern::Literal(literal) => literal.visit_in(v),
+            Pattern::Rest(pattern) => pattern.visit_in(v),
+            Pattern::Ref(mutability, pattern) => {
+                mutability.visit_in(v);
+                pattern.visit_in(v);
+            }
+            Pattern::RangeExc(from, to) => {
+                from.visit_in(v);
+                to.visit_in(v);
+            }
+            Pattern::RangeInc(from, to) => {
+                from.visit_in(v);
+                to.visit_in(v);
+            }
+            Pattern::Tuple(patterns) => patterns.visit_in(v),
+            Pattern::Array(patterns) => patterns.visit_in(v),
+            Pattern::Struct(path, items) => {
+                path.visit_in(v);
+                items.visit_in(v);
+            }
+            Pattern::TupleStruct(path, patterns) => {
+                path.visit_in(v);
+                patterns.visit_in(v);
+            }
+        }
+    }
+}
+impl Walk for While {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_while(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let While { cond, pass, fail } = self;
+        cond.visit_in(v);
+        pass.visit_in(v);
+        fail.visit_in(v);
+    }
+}
+impl Walk for If {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_if(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let If { cond, pass, fail } = self;
+        cond.visit_in(v);
+        pass.visit_in(v);
+        fail.visit_in(v);
+    }
+}
+impl Walk for For {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_for(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let For { bind, cond, pass, fail } = self;
+        cond.visit_in(v);
+        fail.visit_in(v);
+        bind.visit_in(v);
+        pass.visit_in(v);
+    }
+}
+impl Walk for Else {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_else(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Else { body } = self;
+        body.visit_in(v);
+    }
+}
+impl Walk for Break {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_break(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Break { body } = self;
+        body.visit_in(v);
+    }
+}
+impl Walk for Return {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        v.visit_return(self);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let Return { body } = self;
+        body.visit_in(v);
+    }
+}
+
+// --- BLANKET IMPLEMENTATIONS
+
+impl<T: Walk> Walk for [T] {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        self.iter().for_each(|value| value.visit_in(v));
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        self.iter().for_each(|value| value.children(v));
+    }
+}
+
+impl<T: Walk> Walk for Vec<T> {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        self.as_slice().visit_in(v);
+    }
+
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        self.as_slice().children(v);
+    }
+}
+
+impl<A: Walk, B: Walk> Walk for (A, B) {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let (a, b) = self;
+        a.visit_in(v);
+        b.visit_in(v);
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        let (a, b) = self;
+        a.children(v);
+        b.children(v);
+    }
+}
+
+impl<T: Walk> Walk for Option<T> {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        if let Some(value) = self.as_ref() {
+            value.visit_in(v)
+        }
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        if let Some(value) = self {
+            value.children(v)
+        }
+    }
+}
+
+impl<T: Walk> Walk for Box<T> {
+    #[inline]
+    fn visit_in<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        self.as_ref().visit_in(v)
+    }
+    fn children<'a, V: Visit<'a>>(&'a self, v: &mut V) {
+        self.as_ref().children(v)
+    }
+}

compiler/cl-ast/src/desugar.rs

@@ -0,0 +1,11 @@
+//! Desugaring passes for Conlang
+
+pub mod constant_folder;
+pub mod path_absoluter;
+pub mod squash_groups;
+pub mod while_else;
+
+pub use constant_folder::ConstantFolder;
+pub use path_absoluter::NormalizePaths;
+pub use squash_groups::SquashGroups;
+pub use while_else::WhileElseDesugar;

compiler/cl-ast/src/desugar/constant_folder.rs

@@ -0,0 +1,90 @@
+use crate::{
+    ast::{ExprKind as Ek, *},
+    ast_visitor::{Fold, fold::or_fold_expr_kind},
+};
+
+pub struct ConstantFolder;
+
+macro bin_rule(
+    match ($kind: ident, $head: expr, $tail: expr) {
+        $(($op:ident, $impl:expr, $($ty:ident -> $rety:ident),*)),*$(,)?
+    }
+) {
+    #[allow(clippy::all)]
+    match ($kind, $head, $tail) {
+    $($((   BinaryKind::$op,
+            Expr { kind: ExprKind::Literal(Literal::$ty(a)), .. },
+            Expr { kind: ExprKind::Literal(Literal::$ty(b)), .. },
+        ) => {
+            ExprKind::Literal(Literal::$rety($impl(a, b)))
+        },)*)*
+        (kind, head, tail) => ExprKind::Binary(Binary {
+            kind,
+            parts: Box::new((head, tail)),
+        }),
+    }
+}
+
+macro un_rule(
+    match ($kind: ident, $tail: expr) {
+        $(($op:ident, $impl:expr, $($ty:ident),*)),*$(,)?
+    }
+) {
+    match ($kind, $tail) {
+    $($((UnaryKind::$op, Expr { kind: ExprKind::Literal(Literal::$ty(v)), .. }) => {
+            ExprKind::Literal(Literal::$ty($impl(v)))
+        },)*)*
+        (kind, tail) => ExprKind::Unary(Unary { kind, tail: Box::new(tail) }),
+    }
+}
+
+impl Fold for ConstantFolder {
+    fn fold_expr_kind(&mut self, kind: Ek) -> Ek {
+        match kind {
+            Ek::Group(Group { expr }) => self.fold_expr_kind(expr.kind),
+            Ek::Binary(Binary { kind, parts }) => {
+                let (head, tail) = *parts;
+                bin_rule! (match (kind, self.fold_expr(head), self.fold_expr(tail)) {
+                    (Lt,     |a, b| a < b,  Bool -> Bool, Int -> Bool),
+                    (LtEq,   |a, b| a <= b, Bool -> Bool, Int -> Bool),
+                    (Equal,  |a, b| a == b, Bool -> Bool, Int -> Bool),
+                    (NotEq,  |a, b| a != b, Bool -> Bool, Int -> Bool),
+                    (GtEq,   |a, b| a >= b, Bool -> Bool, Int -> Bool),
+                    (Gt,     |a, b| a > b,  Bool -> Bool, Int -> Bool),
+                    (BitAnd, |a, b| a & b,  Bool -> Bool, Int -> Int),
+                    (BitOr,  |a, b| a | b,  Bool -> Bool, Int -> Int),
+                    (BitXor, |a, b| a ^ b,  Bool -> Bool, Int -> Int),
+                    (Shl,    |a, b| a << b, Int -> Int),
+                    (Shr,    |a, b| a >> b, Int -> Int),
+                    (Add,    |a, b| a + b,  Int -> Int),
+                    (Sub,    |a, b| a - b,  Int -> Int),
+                    (Mul,    |a, b| a * b,  Int -> Int),
+                    (Div,    |a, b| a / b,  Int -> Int),
+                    (Rem,    |a, b| a % b,  Int -> Int),
+                    // Cursed bit-smuggled float shenanigans
+                    (Lt,     |a, b| f64::from_bits(a) < f64::from_bits(b),  Float -> Bool),
+                    (LtEq,   |a, b| f64::from_bits(a) >= f64::from_bits(b), Float -> Bool),
+                    (Equal,  |a, b| f64::from_bits(a) == f64::from_bits(b), Float -> Bool),
+                    (NotEq,  |a, b| f64::from_bits(a) != f64::from_bits(b), Float -> Bool),
+                    (GtEq,   |a, b| f64::from_bits(a) <= f64::from_bits(b), Float -> Bool),
+                    (Gt,     |a, b| f64::from_bits(a) > f64::from_bits(b),  Float -> Bool),
+                    (Add,    |a, b| (f64::from_bits(a) + f64::from_bits(b)).to_bits(),  Float -> Float),
+                    (Sub,    |a, b| (f64::from_bits(a) - f64::from_bits(b)).to_bits(),  Float -> Float),
+                    (Mul,    |a, b| (f64::from_bits(a) * f64::from_bits(b)).to_bits(),  Float -> Float),
+                    (Div,    |a, b| (f64::from_bits(a) / f64::from_bits(b)).to_bits(),  Float -> Float),
+                    (Rem,    |a, b| (f64::from_bits(a) % f64::from_bits(b)).to_bits(),  Float -> Float),
+                })
+            }
+            Ek::Unary(Unary { kind, tail }) => {
+                un_rule! (match (kind, self.fold_expr(*tail)) {
+                    (Not, std::ops::Not::not, Int, Bool),
+                    (Neg, std::ops::Not::not, Bool),
+                    (Neg, |i| -(i as i128) as u128, Int),
+                    (Neg, |f| (-f64::from_bits(f)).to_bits(), Float),
+                    (At, std::ops::Not::not, Float), /* Lmao */
+                })
+            }
+            _ => or_fold_expr_kind(self, kind),
+        }
+    }
+}

compiler/cl-ast/src/desugar/path_absoluter.rs

@@ -0,0 +1,55 @@
+use crate::{ast::*, ast_visitor::Fold};
+
+/// Converts relative paths into absolute paths
+pub struct NormalizePaths {
+    path: Path,
+}
+
+impl NormalizePaths {
+    pub fn new() -> Self {
+        Self { path: Path { absolute: true, parts: vec![] } }
+    }
+    /// Normalizes paths as if they came from within the provided paths
+    pub fn in_path(path: Path) -> Self {
+        Self { path }
+    }
+}
+
+impl Default for NormalizePaths {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl Fold for NormalizePaths {
+    fn fold_module(&mut self, m: Module) -> Module {
+        let Module { name, file } = m;
+        self.path.push(PathPart::Ident(name));
+
+        let name = self.fold_sym(name);
+        let file = file.map(|f| self.fold_file(f));
+
+        self.path.pop();
+        Module { name, file }
+    }
+
+    fn fold_path(&mut self, p: Path) -> Path {
+        if p.absolute {
+            p
+        } else {
+            self.path.clone().concat(&p)
+        }
+    }
+
+    fn fold_use(&mut self, u: Use) -> Use {
+        let Use { absolute, mut tree } = u;
+
+        if !absolute {
+            for segment in self.path.parts.iter().rev() {
+                tree = UseTree::Path(*segment, Box::new(tree))
+            }
+        }
+
+        Use { absolute: true, tree: self.fold_use_tree(tree) }
+    }
+}

compiler/cl-ast/src/desugar/squash_groups.rs

@@ -0,0 +1,14 @@
+//! Squashes group expressions
+use crate::{ast::*, ast_visitor::fold::*};
+
+/// Squashes group expressions
+pub struct SquashGroups;
+
+impl Fold for SquashGroups {
+    fn fold_expr_kind(&mut self, kind: ExprKind) -> ExprKind {
+        match kind {
+            ExprKind::Group(Group { expr }) => self.fold_expr(*expr).kind,
+            _ => or_fold_expr_kind(self, kind),
+        }
+    }
+}

compiler/cl-ast/src/desugar/while_else.rs

@@ -0,0 +1,37 @@
+//! Desugars `while {...} else` expressions
+//! into `loop if {...} else break` expressions
+
+use crate::{ast::*, ast_visitor::fold::Fold};
+use cl_structures::span::Span;
+
+/// Desugars while-else expressions
+/// into loop-if-else-break expressions
+pub struct WhileElseDesugar;
+
+impl Fold for WhileElseDesugar {
+    fn fold_expr(&mut self, e: Expr) -> Expr {
+        let Expr { span, kind } = e;
+        let kind = desugar_while(span, kind);
+        Expr { span: self.fold_span(span), kind: self.fold_expr_kind(kind) }
+    }
+}
+
+/// Desugars while(-else) expressions into loop-if-else-break expressions
+fn desugar_while(span: Span, kind: ExprKind) -> ExprKind {
+    match kind {
+        // work backwards: fail -> break -> if -> loop
+        ExprKind::While(While { cond, pass, fail: Else { body } }) => {
+            // Preserve the else-expression's span, if present, or use the parent's span
+            let fail_span = body.as_ref().map(|body| body.span).unwrap_or(span);
+            let break_expr = Expr { span: fail_span, kind: ExprKind::Break(Break { body }) };
+
+            let loop_body = If { cond, pass, fail: Else { body: Some(Box::new(break_expr)) } };
+            let loop_body = ExprKind::If(loop_body);
+            ExprKind::Unary(Unary {
+                kind: UnaryKind::Loop,
+                tail: Box::new(Expr { span, kind: loop_body }),
+            })
+        }
+        _ => kind,
+    }
+}

compiler/cl-ast/src/format.rs

@@ -0,0 +1,82 @@
+use delimiters::Delimiters;
+use std::fmt::Write;
+
+impl<W: Write + ?Sized> FmtAdapter for W {}
+pub trait FmtAdapter: Write {
+    fn indent(&mut self) -> Indent<'_, Self> {
+        Indent { f: self }
+    }
+
+    fn delimit(&mut self, delim: Delimiters) -> Delimit<'_, Self> {
+        Delimit::new(self, delim)
+    }
+
+    fn delimit_with(&mut self, open: &'static str, close: &'static str) -> Delimit<'_, Self> {
+        Delimit::new(self, Delimiters { open, close })
+    }
+}
+
+/// Pads text with leading indentation after every newline
+pub struct Indent<'f, F: Write + ?Sized> {
+    f: &'f mut F,
+}
+
+impl<F: Write + ?Sized> Write for Indent<'_, F> {
+    fn write_str(&mut self, s: &str) -> std::fmt::Result {
+        for s in s.split_inclusive('\n') {
+            self.f.write_str(s)?;
+            if s.ends_with('\n') {
+                self.f.write_str("    ")?;
+            }
+        }
+        Ok(())
+    }
+}
+
+/// Prints [Delimiters] around anything formatted with this. Implies [Indent]
+pub struct Delimit<'f, F: Write + ?Sized> {
+    f: Indent<'f, F>,
+    delim: Delimiters,
+}
+impl<'f, F: Write + ?Sized> Delimit<'f, F> {
+    pub fn new(f: &'f mut F, delim: Delimiters) -> Self {
+        let mut f = f.indent();
+        let _ = f.write_str(delim.open);
+        Self { f, delim }
+    }
+}
+impl<F: Write + ?Sized> Drop for Delimit<'_, F> {
+    fn drop(&mut self) {
+        let Self { f: Indent { f, .. }, delim } = self;
+        let _ = f.write_str(delim.close);
+    }
+}
+
+impl<F: Write + ?Sized> Write for Delimit<'_, F> {
+    fn write_str(&mut self, s: &str) -> std::fmt::Result {
+        self.f.write_str(s)
+    }
+}
+
+pub mod delimiters {
+    #![allow(dead_code)]
+    #[derive(Clone, Copy, Debug)]
+    pub struct Delimiters {
+        pub open: &'static str,
+        pub close: &'static str,
+    }
+    /// Delimits with braces decorated with spaces  `" {\n"`, ..., `"\n}"`
+    pub const SPACED_BRACES: Delimiters = Delimiters { open: " {\n", close: "\n}" };
+    /// Delimits with braces on separate lines `{\n`, ..., `\n}`
+    pub const BRACES: Delimiters = Delimiters { open: "{\n", close: "\n}" };
+    /// Delimits with parentheses on separate lines `{\n`, ..., `\n}`
+    pub const PARENS: Delimiters = Delimiters { open: "(\n", close: "\n)" };
+    /// Delimits with square brackets on separate lines `{\n`, ..., `\n}`
+    pub const SQUARE: Delimiters = Delimiters { open: "[\n", close: "\n]" };
+    /// Delimits with braces on the same line `{ `, ..., ` }`
+    pub const INLINE_BRACES: Delimiters = Delimiters { open: "{ ", close: " }" };
+    /// Delimits with parentheses on the same line `( `, ..., ` )`
+    pub const INLINE_PARENS: Delimiters = Delimiters { open: "(", close: ")" };
+    /// Delimits with square brackets on the same line `[ `, ..., ` ]`
+    pub const INLINE_SQUARE: Delimiters = Delimiters { open: "[", close: "]" };
+}

compiler/cl-ast/src/lib.rs

@@ -0,0 +1,23 @@
+//! # The Abstract Syntax Tree
+//! Contains definitions of Conlang AST Nodes.
+//!
+//! # Notable nodes
+//! - [Item] and [ItemKind]: Top-level constructs
+//! - [Stmt] and [StmtKind]: Statements
+//! - [Expr] and [ExprKind]: Expressions
+//!   - [Assign], [Binary], and [Unary] expressions
+//!   - [ModifyKind], [BinaryKind], and [UnaryKind] operators
+//! - [Ty] and [TyKind]: Type qualifiers
+//! - [Pattern]: Pattern matching operators
+//! - [Path]: Path expressions
+#![warn(clippy::all)]
+#![feature(decl_macro)]
+
+pub use ast::*;
+pub use ast_impl::weight_of::WeightOf;
+
+pub mod ast;
+pub mod ast_impl;
+pub mod ast_visitor;
+pub mod desugar;
+pub mod format;

compiler/cl-embed/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "cl-embed"
+version = "0.1.0"
+repository.workspace = true
+authors.workspace = true
+edition.workspace = true
+license.workspace = true
+publish.workspace = true
+
+[dependencies]
+cl-interpret = { path = "../cl-interpret" }
+cl-ast = { path = "../cl-ast" }
+cl-structures = { path = "../cl-structures" }
+cl-lexer = { path = "../cl-lexer" }
+cl-parser = { path = "../cl-parser" }
+
+[dev-dependencies]
+repline = { version = "*", registry = "soft-fish" }

compiler/cl-embed/examples/calculator.rs

@@ -0,0 +1,27 @@
+//! Demonstrates the cl_embed library
+
+use cl_embed::*;
+use repline::{Response, prebaked};
+
+fn main() -> Result<(), repline::Error> {
+    let mut env = Environment::new();
+
+    if let Err(e) = conlang_include!("calculator/expression.cl")(&mut env) {
+        panic!("{e}")
+    }
+
+    prebaked::read_and("", "calc >", "   ? >", |line| {
+        env.bind("line", line);
+
+        let res = conlang! {
+
+            let (expr, rest) = parse(line.chars(), Power::None);
+            execute(expr)
+
+        }(&mut env)?;
+
+        println!("{res}");
+
+        Ok(Response::Accept)
+    })
+}

compiler/cl-embed/examples/calculator/expression.cl

@@ -0,0 +1 @@
+../../../../sample-code/calculator.cl

compiler/cl-embed/src/lib.rs

@@ -0,0 +1,182 @@
+//! Embed Conlang code into your Rust project!
+//!
+//! # This crate is experimental, and has no guarantees of stability.
+#![feature(decl_macro)]
+#![cfg_attr(test, feature(assert_matches))]
+#![allow(unused_imports)]
+
+pub use cl_interpret::{convalue::ConValue as Value, env::Environment};
+
+use cl_ast::{Block, File, Module, ast_visitor::Fold};
+use cl_interpret::{convalue::ConValue, interpret::Interpret};
+use cl_lexer::Lexer;
+use cl_parser::{Parser, error::Error as ParseError, inliner::ModuleInliner};
+use std::{path::Path, sync::OnceLock};
+
+/// Constructs a function which evaluates a Conlang Block
+///
+/// # Examples
+///
+/// Bind and use a variable
+/// ```rust
+/// # fn main() -> Result<(), Box<dyn std::error::Error>> {
+/// use cl_embed::{conlang, Environment, Value};
+///
+/// let mut env = Environment::new();
+///
+/// // Bind a variable named `message` to "Hello, world!"
+/// env.bind("message", "Hello, World!");
+///
+/// let print_hello = conlang!{
+///     println(message);
+/// };
+///
+/// // Run the function
+/// let ret = print_hello(&mut env)?;
+///
+/// // `println` returns Empty
+/// assert!(matches!(ret, Value::Empty));
+///
+/// # Ok(())
+/// # }
+/// ```
+pub macro conlang(
+    $($t:tt)*
+) {{
+    // Parse once
+    static FN: OnceLock<Result<Block, ParseError>> = OnceLock::new();
+
+    |env: &mut Environment| -> Result<ConValue, EvalError> {
+        FN.get_or_init(|| {
+            // TODO: embed the full module tree at compile time
+            let path =
+                AsRef::<Path>::as_ref(&concat!(env!("CARGO_MANIFEST_DIR"), "/../../", file!()))
+                    .with_extension("");
+            let mut mi = ModuleInliner::new(path);
+            let code = mi.fold_block(
+                Parser::new(
+                    concat!(file!(), ":", line!(), ":", column!()),
+                    Lexer::new(stringify!({ $($t)* })),
+                )
+                .parse::<Block>()?,
+            );
+            if let Some((ie, pe)) = mi.into_errs() {
+                for (file, err) in ie {
+                    eprintln!("{}: {err}", file.display());
+                }
+                for (file, err) in pe {
+                    eprintln!("{}: {err}", file.display());
+                }
+            }
+            Ok(code)
+        })
+        .as_ref()
+        .map_err(Clone::clone)?
+        .interpret(env)
+        .map_err(Into::into)
+    }
+}}
+
+pub macro conlang_include{
+    ($path:literal, $name:ident) => {
+        |env: &mut Environment| -> Result<ConValue, EvalError> {
+            // TODO: embed the full module tree at compile time
+            let path = AsRef::<Path>::as_ref(&concat!(env!("CARGO_MANIFEST_DIR"), "/../../", file!()))
+                .with_file_name(concat!($path));
+            let mut mi = ModuleInliner::new(path);
+            let code = mi.fold_module(Module {
+                name: stringify!($name).into(),
+                file: Some(
+                    Parser::new(
+                        concat!(file!(), ":", line!(), ":", column!()),
+                        Lexer::new(include_str!($path)),
+                    )
+                    .parse()?,
+                ),
+            });
+            if let Some((ie, pe)) = mi.into_errs() {
+                for (file, err) in ie {
+                    eprintln!("{}: {err}", file.display());
+                }
+                for (file, err) in pe {
+                    eprintln!("{}: {err}", file.display());
+                }
+            }
+            code.interpret(env).map_err(Into::into)
+        }
+    },
+    ($path:literal) => {
+        |env: &mut Environment| -> Result<ConValue, EvalError> {
+            // TODO: embed the full module tree at compile time
+            let path = AsRef::<Path>::as_ref(&concat!(env!("CARGO_MANIFEST_DIR"), "/../../", file!()))
+                .with_file_name(concat!($path));
+            let mut mi = ModuleInliner::new(path);
+            let code = mi.fold_file(
+                Parser::new(
+                    concat!(file!(), ":", line!(), ":", column!()),
+                    Lexer::new(include_str!($path)),
+                )
+                .parse()?,
+            );
+            if let Some((ie, pe)) = mi.into_errs() {
+                for (file, err) in ie {
+                    eprintln!("{}: {err}", file.display());
+                }
+                for (file, err) in pe {
+                    eprintln!("{}: {err}", file.display());
+                }
+            }
+            code.interpret(env).map_err(Into::into)
+        }
+    }
+}
+
+#[derive(Clone, Debug)]
+pub enum EvalError {
+    Parse(cl_parser::error::Error),
+    Interpret(cl_interpret::error::Error),
+}
+
+impl From<cl_parser::error::Error> for EvalError {
+    fn from(value: cl_parser::error::Error) -> Self {
+        Self::Parse(value)
+    }
+}
+impl From<cl_interpret::error::Error> for EvalError {
+    fn from(value: cl_interpret::error::Error) -> Self {
+        Self::Interpret(value)
+    }
+}
+impl std::error::Error for EvalError {}
+impl std::fmt::Display for EvalError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            EvalError::Parse(error) => error.fmt(f),
+            EvalError::Interpret(error) => error.fmt(f),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::assert_matches::assert_matches;
+
+    use super::*;
+
+    #[test]
+    fn it_works() -> Result<(), EvalError> {
+        let mut env = Environment::new();
+
+        let result = conlang! {
+            fn add(left, right) -> isize {
+                left + right
+            }
+
+            add(2, 2)
+        }(&mut env);
+
+        assert_matches!(result, Ok(Value::Int(4)));
+
+        Ok(())
+    }
+}

compiler/cl-interpret/examples/conlang-run.rs

@@ -0,0 +1,59 @@
+//! A bare-minimum harness to evaluate a Conlang program
+
+use std::{error::Error, path::PathBuf};
+
+use cl_ast::Expr;
+use cl_interpret::{convalue::ConValue, env::Environment};
+use cl_lexer::Lexer;
+use cl_parser::{Parser, inliner::ModuleInliner};
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let mut args = std::env::args();
+
+    let prog = args.next().unwrap();
+    let Some(path) = args.next().map(PathBuf::from) else {
+        println!("Usage: {prog} `file.cl` [ args... ]");
+        return Ok(());
+    };
+
+    let parent = path.parent().unwrap_or("".as_ref());
+
+    let code = std::fs::read_to_string(&path)?;
+    let code = Parser::new(path.display().to_string(), Lexer::new(&code)).parse()?;
+    let code = match ModuleInliner::new(parent).inline(code) {
+        Ok(code) => code,
+        Err((code, ioerrs, perrs)) => {
+            for (p, err) in ioerrs {
+                eprintln!("{}:{err}", p.display());
+            }
+            for (p, err) in perrs {
+                eprintln!("{}:{err}", p.display());
+            }
+            code
+        }
+    };
+
+    let mut env = Environment::new();
+    env.eval(&code)?;
+
+    let main = "main".into();
+    if env.get(main).is_ok() {
+        let args = args
+            .flat_map(|arg| {
+                Parser::new(&arg, Lexer::new(&arg))
+                    .parse::<Expr>()
+                    .map(|arg| env.eval(&arg))
+            })
+            .collect::<Result<Vec<_>, _>>()?;
+
+        match env.call(main, &args) {
+            Ok(ConValue::Empty) => {}
+            Ok(retval) => println!("{retval}"),
+            Err(e) => {
+                panic!("{e}");
+            }
+        }
+    }
+
+    Ok(())
+}

compiler/cl-interpret/examples/fib.rs

@@ -8,9 +8,5 @@ fn main() {
 
 /// Implements the classic recursive definition of fib()
 fn fib(a: i64) -> i64 {
-    if a > 1 {
-        fib(a - 1) + fib(a - 2)
-    } else {
-        1
-    }
+    if a > 1 { fib(a - 1) + fib(a - 2) } else { a }
 }

compiler/cl-interpret/src/builtin.rs

@@ -0,0 +1,410 @@
+#![allow(non_upper_case_globals)]
+
+use crate::{
+    convalue::ConValue,
+    env::Environment,
+    error::{Error, IResult},
+};
+use std::io::{Write, stdout};
+
+/// A function built into the interpreter.
+#[derive(Clone, Copy)]
+pub struct Builtin {
+    /// An identifier to be used during registration
+    pub name: &'static str,
+    /// The signature, displayed when the builtin is printed
+    pub desc: &'static str,
+    /// The function to be run when called
+    pub func: &'static dyn Fn(&mut Environment, &[ConValue]) -> IResult<ConValue>,
+}
+
+impl Builtin {
+    /// Constructs a new Builtin
+    pub const fn new(
+        name: &'static str,
+        desc: &'static str,
+        func: &'static impl Fn(&mut Environment, &[ConValue]) -> IResult<ConValue>,
+    ) -> Builtin {
+        Builtin { name, desc, func }
+    }
+
+    pub const fn description(&self) -> &'static str {
+        self.desc
+    }
+}
+
+impl std::fmt::Debug for Builtin {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("Builtin")
+            .field("description", &self.desc)
+            .finish_non_exhaustive()
+    }
+}
+
+impl std::fmt::Display for Builtin {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(self.desc)
+    }
+}
+
+impl super::Callable for Builtin {
+    fn call(&self, interpreter: &mut Environment, args: &[ConValue]) -> IResult<ConValue> {
+        (self.func)(interpreter, args)
+    }
+
+    fn name(&self) -> cl_ast::Sym {
+        self.name.into()
+    }
+}
+
+/// Turns a function definition into a [Builtin].
+///
+/// ```rust
+/// # use cl_interpret::{builtin::builtin, convalue::ConValue};
+/// let my_builtin = builtin! {
+///     /// Use the `@env` suffix to bind the environment!
+///     /// (needed for recursive calls)
+///     fn my_builtin(ConValue::Bool(b), rest @ ..) @env {
+///         // This is all Rust code!
+///         eprintln!("my_builtin({b}, ..)");
+///         match rest {
+///             [] => Ok(ConValue::Empty),
+///             _ => my_builtin(env, rest), // Can be called as a normal function!
+///         }
+///     }
+/// };
+/// ```
+pub macro builtin(
+    $(#[$($meta:tt)*])*
+    fn $name:ident ($($arg:pat),*$(,)?) $(@$env:tt)? $body:block
+) {{
+    $(#[$($meta)*])*
+    fn $name(_env: &mut Environment, _args: &[ConValue]) -> IResult<ConValue> {
+        // Set up the builtin! environment
+        $(#[allow(unused)]let $env = _env;)?
+        // Allow for single argument `fn foo(args @ ..)` pattern
+        #[allow(clippy::redundant_at_rest_pattern, irrefutable_let_patterns)]
+        let [$($arg),*] = _args else {
+            Err($crate::error::Error::TypeError())?
+        };
+        $body.map(Into::into)
+    }
+    Builtin {
+        name: stringify!($name),
+        desc: stringify![builtin fn $name($($arg),*)],
+        func: &$name,
+    }
+}}
+
+/// Constructs an array of [Builtin]s from pseudo-function definitions
+pub macro builtins($(
+    $(#[$($meta:tt)*])*
+    fn $name:ident ($($args:tt)*) $(@$env:tt)? $body:block
+)*) {
+    [$(builtin!($(#[$($meta)*])* fn $name ($($args)*) $(@$env)? $body)),*]
+}
+
+/// Creates an [Error::BuiltinError] using interpolation of runtime expressions.
+/// See [std::format].
+pub macro error_format ($($t:tt)*) {
+    $crate::error::Error::BuiltinError(format!($($t)*))
+}
+
+pub const Builtins: &[Builtin] = &builtins![
+    /// Unstable variadic format function
+    fn fmt(args @ ..) {
+        use std::fmt::Write;
+        let mut out = String::new();
+        if let Err(e) = args.iter().try_for_each(|arg| write!(out, "{arg}")) {
+            eprintln!("{e}");
+        }
+        Ok(out)
+    }
+
+    /// Prints the arguments in-order, with no separators
+    fn print(args @ ..) {
+        let mut out = stdout().lock();
+        args.iter().try_for_each(|arg| write!(out, "{arg}") ).ok();
+        Ok(())
+    }
+
+    /// Prints the arguments in-order, followed by a newline
+    fn println(args @ ..) {
+        let mut out = stdout().lock();
+        args.iter().try_for_each(|arg| write!(out, "{arg}") ).ok();
+        writeln!(out).ok();
+        Ok(())
+    }
+
+    /// Debug-prints the argument, returning a copy
+    fn dbg(arg) {
+        println!("{arg:?}");
+        Ok(arg.clone())
+    }
+
+    /// Debug-prints the argument
+    fn dbgp(args @ ..) {
+        let mut out = stdout().lock();
+        args.iter().try_for_each(|arg| writeln!(out, "{arg:#?}") ).ok();
+        Ok(())
+    }
+
+    fn panic(args @ ..) @env {
+        use std::fmt::Write;
+        let mut out = String::new();
+        if let Err(e) = args.iter().try_for_each(|arg| write!(out, "{arg}")) {
+            println!("{e}");
+        }
+        let mut stdout = stdout().lock();
+        write!(stdout, "Explicit panic: `").ok();
+        args.iter().try_for_each(|arg| write!(stdout, "{arg}") ).ok();
+        writeln!(stdout, "`").ok();
+        Err(Error::Panic(out))?;
+        Ok(())
+    }
+
+    /// Dumps the environment
+    fn dump() @env {
+        println!("{env}");
+        Ok(())
+    }
+
+    /// Gets all global variables in the environment
+    fn globals() @env {
+        let globals = env.globals();
+        Ok(ConValue::Slice(globals.base, globals.binds.len()))
+    }
+
+    fn builtins() @env {
+        let len = env.globals().binds.len();
+        for builtin in 0..len {
+            if let Some(value @ ConValue::Builtin(_)) = env.get_id(builtin) {
+                println!("{builtin}: {value}")
+            }
+        }
+        Ok(())
+    }
+
+    fn alloca(ConValue::Int(len)) @env {
+        Ok(env.alloca(ConValue::Empty, *len as usize))
+    }
+
+    /// Returns the length of the input list as a [ConValue::Int]
+    fn len(list) @env {
+        Ok(match list {
+            ConValue::Empty => 0,
+            ConValue::Str(s) => s.chars().count() as _,
+            ConValue::String(s) => s.chars().count() as _,
+            ConValue::Ref(r) => {
+                return len(env, &[env.get_id(*r).ok_or(Error::StackOverflow(*r))?.clone()])
+            }
+            ConValue::Slice(_, len) => *len as _,
+            ConValue::Array(arr) => arr.len() as _,
+            ConValue::Tuple(t) => t.len() as _,
+            _ => Err(Error::TypeError())?,
+        })
+    }
+
+    fn push(ConValue::Ref(index), item) @env{
+        let Some(ConValue::Array(v)) = env.get_id_mut(*index) else {
+            Err(Error::TypeError())?
+        };
+
+        let mut items = std::mem::take(v).into_vec();
+        items.push(item.clone());
+        *v = items.into_boxed_slice();
+
+        Ok(ConValue::Empty)
+    }
+
+    fn chars(string) @env {
+        Ok(match string {
+            ConValue::Str(s) => ConValue::Array(s.chars().map(Into::into).collect()),
+            ConValue::String(s) => ConValue::Array(s.chars().map(Into::into).collect()),
+            ConValue::Ref(r) => {
+                return chars(env, &[env.get_id(*r).ok_or(Error::StackOverflow(*r))?.clone()])
+            }
+            _ => Err(Error::TypeError())?,
+        })
+    }
+
+    fn dump_symbols() {
+        println!("{}", cl_structures::intern::string_interner::StringInterner::global());
+        Ok(ConValue::Empty)
+    }
+
+    fn slice_of(ConValue::Ref(arr), ConValue::Int(start)) {
+        Ok(ConValue::Slice(*arr, *start as usize))
+    }
+
+    /// Returns a shark
+    fn shark() {
+        Ok('\u{1f988}')
+    }
+];
+
+pub const Math: &[Builtin] = &builtins![
+    /// Multiplication `a * b`
+    fn mul(lhs, rhs) {
+        Ok(match (lhs, rhs) {
+            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
+            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a * b),
+            _ => Err(Error::TypeError())?
+        })
+    }
+
+    /// Division `a / b`
+    fn div(lhs, rhs) {
+        Ok(match (lhs, rhs){
+            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
+            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a / b),
+            _ => Err(Error::TypeError())?
+        })
+    }
+
+    /// Remainder `a % b`
+    fn rem(lhs, rhs) {
+        Ok(match (lhs, rhs) {
+            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
+            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a % b),
+            _ => Err(Error::TypeError())?,
+        })
+    }
+
+    /// Addition `a + b`
+    fn add(lhs, rhs) {
+        Ok(match (lhs, rhs) {
+            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
+            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a + b),
+            (ConValue::Str(a), ConValue::Str(b)) => (a.to_string() + b).into(),
+            (ConValue::Str(a), ConValue::String(b)) => (a.to_string() + b).into(),
+            (ConValue::String(a), ConValue::Str(b)) => (a.to_string() + b).into(),
+            (ConValue::String(a), ConValue::String(b)) => (a.to_string() + b).into(),
+            (ConValue::Str(s), ConValue::Char(c)) => { let mut s = s.to_string(); s.push(*c); s.into() }
+            (ConValue::String(s), ConValue::Char(c)) => { let mut s = s.to_string(); s.push(*c); s.into() }
+            (ConValue::Char(a), ConValue::Char(b)) => {
+                ConValue::String([a, b].into_iter().collect::<String>())
+            }
+            _ => Err(Error::TypeError())?
+        })
+    }
+
+    /// Subtraction `a - b`
+    fn sub(lhs, rhs) {
+        Ok(match (lhs, rhs) {
+            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
+            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a - b),
+            _ => Err(Error::TypeError())?,
+        })
+    }
+
+    /// Shift Left `a << b`
+    fn shl(lhs, rhs) {
+        Ok(match (lhs, rhs) {
+            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
+            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a << b),
+            _ => Err(Error::TypeError())?,
+        })
+    }
+
+    /// Shift Right `a >> b`
+    fn shr(lhs, rhs) {
+        Ok(match (lhs, rhs) {
+            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
+            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a >> b),
+            _ => Err(Error::TypeError())?,
+        })
+    }
+
+    /// Bitwise And `a & b`
+    fn and(lhs, rhs) {
+        Ok(match (lhs, rhs) {
+            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
+            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a & b),
+            (ConValue::Bool(a), ConValue::Bool(b)) => ConValue::Bool(a & b),
+            _ => Err(Error::TypeError())?,
+        })
+    }
+
+    /// Bitwise Or `a | b`
+    fn or(lhs, rhs) {
+        Ok(match (lhs, rhs) {
+            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
+            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a | b),
+            (ConValue::Bool(a), ConValue::Bool(b)) => ConValue::Bool(a | b),
+            _ => Err(Error::TypeError())?,
+        })
+    }
+
+    /// Bitwise Exclusive Or `a ^ b`
+    fn xor(lhs, rhs) {
+        Ok(match (lhs, rhs) {
+            (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
+            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a ^ b),
+            (ConValue::Bool(a), ConValue::Bool(b)) => ConValue::Bool(a ^ b),
+            _ => Err(Error::TypeError())?,
+        })
+    }
+
+    #[allow(non_snake_case)]
+    fn RangeExc(start, end) @env {
+        Ok(ConValue::TupleStruct("RangeExc".into(), Box::new(Box::new([start.clone(), end.clone()]))))
+    }
+
+    #[allow(non_snake_case)]
+    fn RangeInc(start, end) @env {
+        Ok(ConValue::TupleStruct("RangeInc".into(), Box::new(Box::new([start.clone(), end.clone()]))))
+    }
+
+    #[allow(non_snake_case)]
+    fn RangeTo(end) @env {
+        Ok(ConValue::TupleStruct("RangeTo".into(), Box::new(Box::new([end.clone()]))))
+    }
+
+    #[allow(non_snake_case)]
+    fn RangeToInc(end) @env {
+        Ok(ConValue::TupleStruct("RangeToInc".into(), Box::new(Box::new([end.clone()]))))
+    }
+
+    /// Negates the ConValue
+    fn neg(tail) {
+        Ok(match tail {
+            ConValue::Empty => ConValue::Empty,
+            ConValue::Int(v) => ConValue::Int(v.wrapping_neg()),
+            ConValue::Float(v) => ConValue::Float(-v),
+            _ => Err(Error::TypeError())?,
+        })
+    }
+
+    /// Inverts the ConValue
+    fn not(tail) {
+        Ok(match tail {
+            ConValue::Empty => ConValue::Empty,
+            ConValue::Int(v) => ConValue::Int(!v),
+            ConValue::Bool(v) => ConValue::Bool(!v),
+            _ => Err(Error::TypeError())?,
+        })
+    }
+
+    /// Compares two values
+    fn cmp(head, tail) {
+        Ok(ConValue::Int(match (head, tail) {
+            (ConValue::Int(a), ConValue::Int(b)) => a.cmp(b) as _,
+            (ConValue::Bool(a), ConValue::Bool(b)) => a.cmp(b) as _,
+            (ConValue::Char(a), ConValue::Char(b)) => a.cmp(b) as _,
+            (ConValue::Str(a), ConValue::Str(b)) => a.cmp(b) as _,
+            (ConValue::Str(a), ConValue::String(b)) => a.to_ref().cmp(b.as_str()) as _,
+            (ConValue::String(a), ConValue::Str(b)) => a.as_str().cmp(b.to_ref()) as _,
+            (ConValue::String(a), ConValue::String(b)) => a.cmp(b) as _,
+            _ => Err(error_format!("Incomparable values: {head}, {tail}"))?
+        }))
+    }
+
+    /// Does the opposite of `&`
+    fn deref(tail) @env {
+        Ok(match tail {
+            ConValue::Ref(v) => env.get_id(*v).cloned().ok_or(Error::StackOverflow(*v))?,
+            _ => tail.clone(),
+        })
+    }
+];

compiler/cl-interpret/src/closure.rs

@@ -0,0 +1,68 @@
+use crate::{
+    Callable,
+    convalue::ConValue,
+    env::Environment,
+    error::{Error, ErrorKind, IResult},
+    function::collect_upvars::CollectUpvars,
+    interpret::Interpret,
+    pattern,
+};
+use cl_ast::{Sym, ast_visitor::Visit};
+use std::{collections::HashMap, fmt::Display};
+
+/// Represents an ad-hoc anonymous function
+/// which captures surrounding state by COPY
+#[derive(Clone, Debug)]
+pub struct Closure {
+    decl: cl_ast::Closure,
+    lift: HashMap<Sym, ConValue>,
+}
+
+impl Closure {
+    const NAME: &'static str = "{closure}";
+}
+
+impl Closure {
+    pub fn new(env: &mut Environment, decl: &cl_ast::Closure) -> Self {
+        let lift = CollectUpvars::new(env).visit(decl).finish_copied();
+        Self { decl: decl.clone(), lift }
+    }
+}
+
+impl Display for Closure {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { decl, lift: _ } = self;
+        write!(f, "{decl}")
+    }
+}
+
+impl Callable for Closure {
+    fn call(&self, env: &mut Environment, args: &[ConValue]) -> IResult<ConValue> {
+        let Self { decl, lift } = self;
+        let mut env = env.frame(Self::NAME);
+
+        // place lifts in scope
+        for (name, value) in lift.clone() {
+            env.insert(name, value);
+        }
+
+        let mut env = env.frame("args");
+
+        for (name, value) in pattern::substitution(&env, &decl.arg, ConValue::Tuple(args.into()))? {
+            env.insert(name, value);
+        }
+
+        let res = decl.body.interpret(&mut env);
+        drop(env);
+
+        match res {
+            Err(Error { kind: ErrorKind::Return(value), .. }) => Ok(value),
+            Err(Error { kind: ErrorKind::Break(value), .. }) => Err(Error::BadBreak(value)),
+            other => other,
+        }
+    }
+
+    fn name(&self) -> cl_ast::Sym {
+        Self::NAME.into()
+    }
+}

compiler/cl-interpret/src/convalue.rs

@@ -0,0 +1,449 @@
+//! Values in the dynamically typed AST interpreter.
+//!
+//! The most permanent fix is a temporary one.
+use cl_ast::{Expr, Sym, format::FmtAdapter};
+
+use crate::{closure::Closure, constructor::Constructor};
+
+use super::{
+    Callable, Environment,
+    builtin::Builtin,
+    error::{Error, IResult},
+    function::Function,
+};
+use std::{collections::HashMap, ops::*, rc::Rc};
+
+/*
+A Value can be:
+- A Primitive (Empty, isize, etc.)
+- A Record (Array, Tuple, Struct)
+- A Variant (discriminant, Value) pair
+
+array [
+    10,     // 0
+    20,     // 1
+]
+
+tuple (
+    10,     // 0
+    20,     // 1
+)
+
+struct {
+    x: 10,  // x => 0
+    y: 20,  // y => 1
+}
+*/
+
+type Integer = isize;
+
+/// A Conlang value stores data in the interpreter
+#[derive(Clone, Debug, Default)]
+pub enum ConValue {
+    /// The empty/unit `()` type
+    #[default]
+    Empty,
+    /// An integer
+    Int(Integer),
+    /// A floating point number
+    Float(f64),
+    /// A boolean
+    Bool(bool),
+    /// A unicode character
+    Char(char),
+    /// A string literal
+    Str(Sym),
+    /// A dynamic string
+    String(String),
+    /// A reference
+    Ref(usize),
+    /// A reference to an array
+    Slice(usize, usize),
+    /// An Array
+    Array(Box<[ConValue]>),
+    /// A tuple
+    Tuple(Box<[ConValue]>),
+    // TODO: Instead of storing the identifier, store the index of the struct module
+    /// A value of a product type
+    Struct(Sym, Box<HashMap<Sym, ConValue>>),
+    /// A value of a product type with anonymous members
+    TupleStruct(Sym, Box<Box<[ConValue]>>),
+    /// An entire namespace
+    Module(Box<HashMap<Sym, ConValue>>),
+    /// A quoted expression
+    Quote(Rc<Expr>),
+    /// A callable thing
+    Function(Rc<Function>),
+    /// A tuple constructor
+    TupleConstructor(Constructor),
+    /// A closure, capturing by reference
+    Closure(Rc<Closure>),
+    /// A built-in function
+    Builtin(&'static Builtin),
+}
+
+impl ConValue {
+    /// Gets whether the current value is true or false
+    pub fn truthy(&self) -> IResult<bool> {
+        match self {
+            ConValue::Bool(v) => Ok(*v),
+            _ => Err(Error::TypeError())?,
+        }
+    }
+
+    pub fn typename(&self) -> &'static str {
+        match self {
+            ConValue::Empty => "Empty",
+            ConValue::Int(_) => "i64",
+            ConValue::Float(_) => "f64",
+            ConValue::Bool(_) => "bool",
+            ConValue::Char(_) => "char",
+            ConValue::Str(_) => "str",
+            ConValue::String(_) => "String",
+            ConValue::Ref(_) => "Ref",
+            ConValue::Slice(_, _) => "Slice",
+            ConValue::Array(_) => "Array",
+            ConValue::Tuple(_) => "Tuple",
+            ConValue::Struct(_, _) => "Struct",
+            ConValue::TupleStruct(_, _) => "TupleStruct",
+            ConValue::Module(_) => "",
+            ConValue::Quote(_) => "Quote",
+            ConValue::Function(_) => "Fn",
+            ConValue::TupleConstructor(_) => "Fn",
+            ConValue::Closure(_) => "Fn",
+            ConValue::Builtin(_) => "Fn",
+        }
+    }
+
+    #[allow(non_snake_case)]
+    pub fn TupleStruct(id: Sym, values: Box<[ConValue]>) -> Self {
+        Self::TupleStruct(id, Box::new(values))
+    }
+    #[allow(non_snake_case)]
+    pub fn Struct(id: Sym, values: HashMap<Sym, ConValue>) -> Self {
+        Self::Struct(id, Box::new(values))
+    }
+
+    pub fn index(&self, index: &Self, _env: &Environment) -> IResult<ConValue> {
+        let &Self::Int(index) = index else {
+            Err(Error::TypeError())?
+        };
+        match self {
+            ConValue::Str(string) => string
+                .chars()
+                .nth(index as _)
+                .map(ConValue::Char)
+                .ok_or(Error::OobIndex(index as usize, string.chars().count())),
+            ConValue::String(string) => string
+                .chars()
+                .nth(index as _)
+                .map(ConValue::Char)
+                .ok_or(Error::OobIndex(index as usize, string.chars().count())),
+            ConValue::Array(arr) => arr
+                .get(index as usize)
+                .cloned()
+                .ok_or(Error::OobIndex(index as usize, arr.len())),
+            &ConValue::Slice(id, len) => {
+                let index = if index < 0 {
+                    len.wrapping_add_signed(index)
+                } else {
+                    index as usize
+                };
+                if index < len {
+                    Ok(ConValue::Ref(id + index))
+                } else {
+                    Err(Error::OobIndex(index, len))
+                }
+            }
+            _ => Err(Error::TypeError()),
+        }
+    }
+    cmp! {
+        lt: false, <;
+        lt_eq: true, <=;
+        eq: true, ==;
+        neq: false, !=;
+        gt_eq: true, >=;
+        gt: false, >;
+    }
+    assign! {
+        add_assign: +;
+        bitand_assign: &;
+        bitor_assign: |;
+        bitxor_assign: ^;
+        div_assign: /;
+        mul_assign: *;
+        rem_assign: %;
+        shl_assign: <<;
+        shr_assign: >>;
+        sub_assign: -;
+    }
+}
+
+impl Callable for ConValue {
+    fn name(&self) -> Sym {
+        match self {
+            ConValue::Function(func) => func.name(),
+            ConValue::Closure(func) => func.name(),
+            ConValue::Builtin(func) => func.name(),
+            _ => "".into(),
+        }
+    }
+    fn call(&self, env: &mut Environment, args: &[ConValue]) -> IResult<ConValue> {
+        match self {
+            Self::Function(func) => func.call(env, args),
+            Self::TupleConstructor(func) => func.call(env, args),
+            Self::Closure(func) => func.call(env, args),
+            Self::Builtin(func) => func.call(env, args),
+            Self::Module(m) => {
+                if let Some(func) = m.get(&"call".into()) {
+                    func.call(env, args)
+                } else {
+                    Err(Error::NotCallable(self.clone()))
+                }
+            }
+            &Self::Ref(ptr) => {
+                // Move onto stack, and call
+                let func = env.get_id(ptr).ok_or(Error::StackOverflow(ptr))?.clone();
+                func.call(env, args)
+            }
+            _ => Err(Error::NotCallable(self.clone())),
+        }
+    }
+}
+/// Templates comparison functions for [ConValue]
+macro cmp ($($fn:ident: $empty:literal, $op:tt);*$(;)?) {$(
+    /// TODO: Remove when functions are implemented:
+    ///       Desugar into function calls
+    pub fn $fn(&self, other: &Self) -> IResult<Self> {
+        match (self, other) {
+            (Self::Empty, Self::Empty) => Ok(Self::Bool($empty)),
+            (Self::Int(a), Self::Int(b)) => Ok(Self::Bool(a $op b)),
+            (Self::Float(a), Self::Float(b)) => Ok(Self::Bool(a $op b)),
+            (Self::Bool(a), Self::Bool(b)) => Ok(Self::Bool(a $op b)),
+            (Self::Char(a), Self::Char(b)) => Ok(Self::Bool(a $op b)),
+            (Self::Str(a), Self::Str(b)) => Ok(Self::Bool(&**a $op &**b)),
+            (Self::Str(a), Self::String(b)) => Ok(Self::Bool(&**a $op &**b)),
+            (Self::String(a), Self::Str(b)) => Ok(Self::Bool(&**a $op &**b)),
+            (Self::String(a), Self::String(b)) => Ok(Self::Bool(&**a $op &**b)),
+            _ => Err(Error::TypeError())
+        }
+    }
+)*}
+macro assign($( $fn: ident: $op: tt );*$(;)?) {$(
+    pub fn $fn(&mut self, other: Self) -> IResult<()> {
+        *self = (std::mem::take(self) $op other)?;
+        Ok(())
+    }
+)*}
+/// Implements [From] for an enum with 1-tuple variants
+macro from ($($T:ty => $v:expr),*$(,)?) {
+    $(impl From<$T> for ConValue {
+        fn from(value: $T) -> Self { $v(value.into()) }
+    })*
+}
+impl From<&Sym> for ConValue {
+    fn from(value: &Sym) -> Self {
+        ConValue::Str(*value)
+    }
+}
+from! {
+    Integer => ConValue::Int,
+    f64 => ConValue::Float,
+    bool => ConValue::Bool,
+    char => ConValue::Char,
+    Sym => ConValue::Str,
+    &str => ConValue::Str,
+    Expr => ConValue::Quote,
+    String => ConValue::String,
+    Rc<str> => ConValue::Str,
+    Function => ConValue::Function,
+    Vec<ConValue> => ConValue::Tuple,
+    &'static Builtin => ConValue::Builtin,
+}
+impl From<()> for ConValue {
+    fn from(_: ()) -> Self {
+        Self::Empty
+    }
+}
+impl From<&[ConValue]> for ConValue {
+    fn from(value: &[ConValue]) -> Self {
+        match value {
+            [] => Self::Empty,
+            [value] => value.clone(),
+            _ => Self::Tuple(value.into()),
+        }
+    }
+}
+
+/// Implements binary [std::ops] traits for [ConValue]
+///
+/// TODO: Desugar operators into function calls
+macro ops($($trait:ty: $fn:ident = [$($match:tt)*])*) {
+    $(impl $trait for ConValue {
+        type Output = IResult<Self>;
+        /// TODO: Desugar operators into function calls
+        fn $fn(self, rhs: Self) -> Self::Output {Ok(match (self, rhs) {$($match)*})}
+    })*
+}
+ops! {
+    Add: add = [
+        (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
+        (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a.wrapping_add(b)),
+        (ConValue::Float(a), ConValue::Float(b)) => ConValue::Float(a + b),
+        (ConValue::Str(a), ConValue::Str(b)) => (a.to_string() + &*b).into(),
+        (ConValue::Str(a), ConValue::String(b)) => (a.to_string() + &*b).into(),
+        (ConValue::String(a), ConValue::Str(b)) => (a.to_string() + &*b).into(),
+        (ConValue::String(a), ConValue::String(b)) => (a.to_string() + &*b).into(),
+        (ConValue::Str(s), ConValue::Char(c)) => { let mut s = s.to_string(); s.push(c); s.into() }
+        (ConValue::String(s), ConValue::Char(c)) => { let mut s = s.to_string(); s.push(c); s.into() }
+        (ConValue::Char(a), ConValue::Char(b)) => {
+            ConValue::String([a, b].into_iter().collect::<String>())
+        }
+        _ => Err(Error::TypeError())?
+        ]
+    BitAnd: bitand = [
+        (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
+        (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a & b),
+        (ConValue::Bool(a), ConValue::Bool(b)) => ConValue::Bool(a & b),
+        _ => Err(Error::TypeError())?
+    ]
+    BitOr: bitor = [
+        (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
+        (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a | b),
+        (ConValue::Bool(a), ConValue::Bool(b)) => ConValue::Bool(a | b),
+        _ => Err(Error::TypeError())?
+    ]
+    BitXor: bitxor = [
+        (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
+        (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a ^ b),
+        (ConValue::Bool(a), ConValue::Bool(b)) => ConValue::Bool(a ^ b),
+        _ => Err(Error::TypeError())?
+    ]
+    Div: div = [
+        (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
+        (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a.checked_div(b).unwrap_or_else(|| {
+            eprintln!("Warning: Divide by zero in {a} / {b}"); a
+        })),
+        (ConValue::Float(a), ConValue::Float(b)) => ConValue::Float(a / b),
+        _ => Err(Error::TypeError())?
+    ]
+    Mul: mul = [
+        (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
+        (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a.wrapping_mul(b)),
+        (ConValue::Float(a), ConValue::Float(b)) => ConValue::Float(a * b),
+        _ => Err(Error::TypeError())?
+    ]
+    Rem: rem = [
+        (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
+        (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a.checked_rem(b).unwrap_or_else(|| {
+            println!("Warning: Divide by zero in {a} % {b}"); a
+        })),
+        (ConValue::Float(a), ConValue::Float(b)) => ConValue::Float(a % b),
+        _ => Err(Error::TypeError())?
+    ]
+    Shl: shl = [
+        (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
+        (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a.wrapping_shl(b as _)),
+        _ => Err(Error::TypeError())?
+    ]
+    Shr: shr = [
+        (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
+        (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a.wrapping_shr(b as _)),
+        _ => Err(Error::TypeError())?
+    ]
+    Sub: sub = [
+        (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
+        (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a.wrapping_sub(b)),
+        (ConValue::Float(a), ConValue::Float(b)) => ConValue::Float(a - b),
+        _ => Err(Error::TypeError())?
+    ]
+}
+impl std::fmt::Display for ConValue {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            ConValue::Empty => "Empty".fmt(f),
+            ConValue::Int(v) => v.fmt(f),
+            ConValue::Float(v) => v.fmt(f),
+            ConValue::Bool(v) => v.fmt(f),
+            ConValue::Char(v) => v.fmt(f),
+            ConValue::Str(v) => v.fmt(f),
+            ConValue::String(v) => v.fmt(f),
+            ConValue::Ref(v) => write!(f, "&<{}>", v),
+            ConValue::Slice(id, len) => write!(f, "&<{id}>[{len}..]"),
+            ConValue::Array(array) => {
+                '['.fmt(f)?;
+                for (idx, element) in array.iter().enumerate() {
+                    if idx > 0 {
+                        ", ".fmt(f)?
+                    }
+                    element.fmt(f)?
+                }
+                ']'.fmt(f)
+            }
+            ConValue::Tuple(tuple) => {
+                '('.fmt(f)?;
+                for (idx, element) in tuple.iter().enumerate() {
+                    if idx > 0 {
+                        ", ".fmt(f)?
+                    }
+                    element.fmt(f)?
+                }
+                ')'.fmt(f)
+            }
+            ConValue::TupleStruct(id, tuple) => {
+                write!(f, "{id}")?;
+                '('.fmt(f)?;
+                for (idx, element) in tuple.iter().enumerate() {
+                    if idx > 0 {
+                        ", ".fmt(f)?
+                    }
+                    element.fmt(f)?
+                }
+                ')'.fmt(f)
+            }
+            ConValue::Struct(id, map) => {
+                use std::fmt::Write;
+                write!(f, "{id} ")?;
+                let mut f = f.delimit_with("{", "\n}");
+                for (k, v) in map.iter() {
+                    write!(f, "\n{k}: {v},")?;
+                }
+                Ok(())
+            }
+            ConValue::Module(module) => {
+                use std::fmt::Write;
+                let mut f = f.delimit_with("{", "\n}");
+                for (k, v) in module.iter() {
+                    write!(f, "\n{k}: {v},")?;
+                }
+                Ok(())
+            }
+            ConValue::Quote(q) => {
+                write!(f, "`{q}`")
+            }
+            ConValue::Function(func) => {
+                write!(f, "{}", func.decl())
+            }
+            ConValue::TupleConstructor(Constructor { name: index, arity }) => {
+                write!(f, "{index}(..{arity})")
+            }
+            ConValue::Closure(func) => {
+                write!(f, "{}", func.as_ref())
+            }
+            ConValue::Builtin(func) => {
+                write!(f, "{}", func)
+            }
+        }
+    }
+}
+
+pub macro cvstruct (
+    $Name:ident {
+        $($member:ident : $expr:expr),*
+    }
+) {{
+    let mut members = HashMap::new();
+    $(members.insert(stringify!($member).into(), ($expr).into());)*
+    ConValue::Struct(Box::new((stringify!($Name).into(), members)))
+}}

compiler/cl-interpret/src/env.rs

@@ -0,0 +1,310 @@
+//! Lexical and non-lexical scoping for variables
+
+use crate::{builtin::Builtin, constructor::Constructor, modules::ModuleTree};
+
+use super::{
+    Callable, Interpret,
+    builtin::{Builtins, Math},
+    convalue::ConValue,
+    error::{Error, IResult},
+    function::Function,
+};
+use cl_ast::{Function as FnDecl, Sym};
+use std::{
+    collections::HashMap,
+    fmt::Display,
+    ops::{Deref, DerefMut},
+    rc::Rc,
+};
+
+pub type StackFrame = HashMap<Sym, ConValue>;
+
+pub type StackBinds = HashMap<Sym, usize>;
+
+#[derive(Clone, Debug, Default)]
+pub(crate) struct EnvFrame {
+    pub name: Option<&'static str>,
+    /// The length of the array when this stack frame was constructed
+    pub base: usize,
+    /// The bindings of name to stack position
+    pub binds: StackBinds,
+}
+
+/// Implements a nested lexical scope
+#[derive(Clone, Debug)]
+pub struct Environment {
+    values: Vec<ConValue>,
+    frames: Vec<EnvFrame>,
+    modules: ModuleTree,
+}
+
+impl Display for Environment {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        for EnvFrame { name, base: _, binds } in self.frames.iter().rev() {
+            writeln!(
+                f,
+                "--- {}[{}] ---",
+                if let Some(name) = name { name } else { "" },
+                binds.len(),
+            )?;
+            let mut binds: Vec<_> = binds.iter().collect();
+            binds.sort_by(|(_, a), (_, b)| a.cmp(b));
+            for (name, idx) in binds {
+                write!(f, "{idx:4} {name}: ")?;
+                match self.values.get(*idx) {
+                    Some(value) => writeln!(f, "\t{value}"),
+                    None => writeln!(f, "ERROR: {name}'s address blows the stack!"),
+                }?
+            }
+        }
+        Ok(())
+    }
+}
+
+impl Default for Environment {
+    fn default() -> Self {
+        let mut this = Self::no_builtins();
+        this.add_builtins(Builtins).add_builtins(Math);
+        this
+    }
+}
+
+impl Environment {
+    pub fn new() -> Self {
+        Self::default()
+    }
+    /// Creates an [Environment] with no [builtins](super::builtin)
+    pub fn no_builtins() -> Self {
+        Self {
+            values: Vec::new(),
+            frames: vec![EnvFrame::default()],
+            modules: ModuleTree::default(),
+        }
+    }
+
+    /// Reflexively evaluates a node
+    pub fn eval(&mut self, node: &impl Interpret) -> IResult<ConValue> {
+        node.interpret(self)
+    }
+
+    /// Calls a function inside the Environment's scope,
+    /// and returns the result
+    pub fn call(&mut self, name: Sym, args: &[ConValue]) -> IResult<ConValue> {
+        let function = self.get(name)?;
+        function.call(self, args)
+    }
+
+    pub fn modules_mut(&mut self) -> &mut ModuleTree {
+        &mut self.modules
+    }
+
+    pub fn modules(&self) -> &ModuleTree {
+        &self.modules
+    }
+
+    /// Binds a value to the given name in the current scope.
+    pub fn bind(&mut self, name: impl Into<Sym>, value: impl Into<ConValue>) {
+        self.insert(name.into(), value.into());
+    }
+
+    pub fn bind_raw(&mut self, name: Sym, id: usize) -> Option<()> {
+        let EnvFrame { name: _, base: _, binds } = self.frames.last_mut()?;
+        binds.insert(name, id);
+        Some(())
+    }
+
+    /// Gets all registered globals, bound or unbound.
+    pub(crate) fn globals(&self) -> &EnvFrame {
+        self.frames.first().unwrap()
+    }
+
+    /// Adds builtins
+    ///
+    /// # Panics
+    ///
+    /// Will panic if stack contains more than the globals frame!
+    pub fn add_builtins(&mut self, builtins: &'static [Builtin]) -> &mut Self {
+        if self.frames.len() != 1 {
+            panic!("Cannot add builtins to full stack: {self}")
+        }
+
+        for builtin in builtins {
+            self.insert(builtin.name(), builtin.into());
+        }
+
+        self
+    }
+
+    pub fn push_frame(&mut self, name: &'static str, frame: StackFrame) {
+        self.frames.push(EnvFrame {
+            name: Some(name),
+            base: self.values.len(),
+            binds: HashMap::new(),
+        });
+        for (k, v) in frame {
+            self.insert(k, v);
+        }
+    }
+
+    pub fn pop_frame(&mut self) -> Option<(StackFrame, &'static str)> {
+        let mut out = HashMap::new();
+        let EnvFrame { name, base, binds } = self.frames.pop()?;
+        for (k, v) in binds {
+            out.insert(k, self.values.get_mut(v).map(std::mem::take)?);
+        }
+        self.values.truncate(base);
+        Some((out, name.unwrap_or("")))
+    }
+
+    /// Enters a nested scope, returning a [`Frame`] stack-guard.
+    ///
+    /// [`Frame`] implements Deref/DerefMut for [`Environment`].
+    pub fn frame(&mut self, name: &'static str) -> Frame<'_> {
+        Frame::new(self, name)
+    }
+
+    /// Enters a nested scope, assigning the contents of `frame`,
+    /// and returning a [`Frame`] stack-guard.
+    ///
+    /// [`Frame`] implements Deref/DerefMut for [`Environment`].
+    pub fn with_frame<'e>(&'e mut self, name: &'static str, frame: StackFrame) -> Frame<'e> {
+        let mut scope = self.frame(name);
+        for (k, v) in frame {
+            scope.insert(k, v);
+        }
+        scope
+    }
+
+    /// Resolves a variable mutably.
+    ///
+    /// Returns a mutable reference to the variable's record, if it exists.
+    pub fn get_mut(&mut self, name: Sym) -> IResult<&mut ConValue> {
+        let at = self.id_of(name)?;
+        self.get_id_mut(at).ok_or(Error::NotDefined(name))
+    }
+
+    /// Resolves a variable immutably.
+    ///
+    /// Returns a reference to the variable's contents, if it is defined and initialized.
+    pub fn get(&self, name: Sym) -> IResult<ConValue> {
+        let id = self.id_of(name)?;
+        let res = self.values.get(id);
+        Ok(res.ok_or(Error::NotDefined(name))?.clone())
+    }
+
+    /// Resolves the index associated with a [Sym]
+    pub fn id_of(&self, name: Sym) -> IResult<usize> {
+        for EnvFrame { binds, .. } in self.frames.iter().rev() {
+            if let Some(id) = binds.get(&name).copied() {
+                return Ok(id);
+            }
+        }
+        Err(Error::NotDefined(name))
+    }
+
+    pub fn get_id(&self, id: usize) -> Option<&ConValue> {
+        self.values.get(id)
+    }
+
+    pub fn get_id_mut(&mut self, id: usize) -> Option<&mut ConValue> {
+        self.values.get_mut(id)
+    }
+
+    pub fn get_slice(&self, start: usize, len: usize) -> Option<&[ConValue]> {
+        self.values.get(start..start + len)
+    }
+
+    pub fn get_slice_mut(&mut self, start: usize, len: usize) -> Option<&mut [ConValue]> {
+        self.values.get_mut(start..start + len)
+    }
+
+    /// Inserts a new [ConValue] into this [Environment]
+    pub fn insert(&mut self, k: Sym, v: ConValue) {
+        if self.bind_raw(k, self.values.len()).is_some() {
+            self.values.push(v);
+        }
+    }
+
+    /// A convenience function for registering a [FnDecl] as a [Function]
+    pub fn insert_fn(&mut self, decl: &FnDecl) {
+        let FnDecl { name, .. } = decl;
+        let (name, function) = (*name, Rc::new(Function::new(decl)));
+        self.insert(name, ConValue::Function(function.clone()));
+        // Tell the function to lift its upvars now, after it's been declared
+        function.lift_upvars(self);
+    }
+
+    pub fn insert_tup_constructor(&mut self, name: Sym, arity: usize) {
+        let cs = Constructor { arity: arity as _, name };
+        self.insert(name, ConValue::TupleConstructor(cs));
+    }
+
+    /// Gets the current stack top position
+    pub fn pos(&self) -> usize {
+        self.values.len()
+    }
+
+    /// Allocates a local variable
+    pub fn stack_alloc(&mut self, value: ConValue) -> IResult<usize> {
+        let adr = self.values.len();
+        self.values.push(value);
+        Ok(adr)
+    }
+
+    /// Allocates some space on the stack
+    pub fn alloca(&mut self, value: ConValue, len: usize) -> ConValue {
+        let idx = self.values.len();
+        self.values.extend(std::iter::repeat_n(value, len));
+        ConValue::Slice(idx, len)
+    }
+}
+
+/// Represents a stack frame
+#[derive(Debug)]
+pub struct Frame<'scope> {
+    scope: &'scope mut Environment,
+}
+impl<'scope> Frame<'scope> {
+    fn new(scope: &'scope mut Environment, name: &'static str) -> Self {
+        scope.frames.push(EnvFrame {
+            name: Some(name),
+            base: scope.values.len(),
+            binds: HashMap::new(),
+        });
+
+        Self { scope }
+    }
+
+    pub fn pop_values(mut self) -> Option<StackFrame> {
+        let mut out = HashMap::new();
+        let binds = std::mem::take(&mut self.frames.last_mut()?.binds);
+        for (k, v) in binds {
+            out.insert(k, self.values.get_mut(v).map(std::mem::take)?);
+        }
+        Some(out)
+    }
+
+    pub fn into_binds(mut self) -> Option<StackBinds> {
+        let EnvFrame { name: _, base: _, binds } = self.frames.pop()?;
+        std::mem::forget(self);
+        Some(binds)
+    }
+}
+impl Deref for Frame<'_> {
+    type Target = Environment;
+    fn deref(&self) -> &Self::Target {
+        self.scope
+    }
+}
+impl DerefMut for Frame<'_> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        self.scope
+    }
+}
+impl Drop for Frame<'_> {
+    fn drop(&mut self) {
+        if let Some(frame) = self.frames.pop() {
+            self.values.truncate(frame.base);
+        }
+    }
+}

compiler/cl-interpret/src/error.rs

@@ -0,0 +1,218 @@
+//! The [Error] type represents any error thrown by the [Environment](super::Environment)
+
+use cl_ast::{Pattern, Sym};
+use cl_structures::span::Span;
+
+use super::convalue::ConValue;
+
+pub type IResult<T> = Result<T, Error>;
+
+#[derive(Clone, Debug)]
+pub struct Error {
+    pub kind: ErrorKind,
+    pub(super) span: Option<Span>,
+}
+
+impl Error {
+    #![allow(non_snake_case)]
+
+    /// Adds a [struct Span] to this [Error], if there isn't already a more specific one.
+    pub fn with_span(self, span: Span) -> Self {
+        Self { span: self.span.or(Some(span)), ..self }
+    }
+
+    pub fn kind(&self) -> &ErrorKind {
+        &self.kind
+    }
+
+    /// Propagate a Return value
+    pub fn Return(value: ConValue) -> Self {
+        Self { kind: ErrorKind::Return(value), span: None }
+    }
+    /// Propagate a Break value
+    pub fn Break(value: ConValue) -> Self {
+        Self { kind: ErrorKind::Break(value), span: None }
+    }
+    /// Break propagated across function bounds
+    pub fn BadBreak(value: ConValue) -> Self {
+        Self { kind: ErrorKind::BadBreak(value), span: None }
+    }
+    /// Continue to the next iteration of a loop
+    pub fn Continue() -> Self {
+        Self { kind: ErrorKind::Continue, span: None }
+    }
+    /// Underflowed the stack
+    pub fn StackUnderflow() -> Self {
+        Self { kind: ErrorKind::StackUnderflow, span: None }
+    }
+    /// Overflowed the stack
+    pub fn StackOverflow(place: usize) -> Self {
+        Self { kind: ErrorKind::StackOverflow(place), span: None }
+    }
+    /// Exited the last scope
+    pub fn ScopeExit() -> Self {
+        Self { kind: ErrorKind::ScopeExit, span: None }
+    }
+    /// Type incompatibility
+    // TODO: store the type information in this error
+    pub fn TypeError() -> Self {
+        Self { kind: ErrorKind::TypeError, span: None }
+    }
+    /// In clause of For loop didn't yield a Range
+    pub fn NotIterable() -> Self {
+        Self { kind: ErrorKind::NotIterable, span: None }
+    }
+    /// A value could not be indexed
+    pub fn NotIndexable() -> Self {
+        Self { kind: ErrorKind::NotIndexable, span: None }
+    }
+    /// An array index went out of bounds
+    pub fn OobIndex(index: usize, length: usize) -> Self {
+        Self { kind: ErrorKind::OobIndex(index, length), span: None }
+    }
+    /// An expression is not assignable
+    pub fn NotAssignable() -> Self {
+        Self { kind: ErrorKind::NotAssignable, span: None }
+    }
+    /// A name was not defined in scope before being used
+    pub fn NotDefined(name: Sym) -> Self {
+        Self { kind: ErrorKind::NotDefined(name), span: None }
+    }
+    /// A name was defined but not initialized
+    pub fn NotInitialized(name: Sym) -> Self {
+        Self { kind: ErrorKind::NotInitialized(name), span: None }
+    }
+    /// A value was called, but is not callable
+    pub fn NotCallable(value: ConValue) -> Self {
+        Self { kind: ErrorKind::NotCallable(value), span: None }
+    }
+    /// A function was called with the wrong number of arguments
+    pub fn ArgNumber(want: usize, got: usize) -> Self {
+        Self { kind: ErrorKind::ArgNumber { want, got }, span: None }
+    }
+    /// A pattern failed to match
+    pub fn PatFailed(pat: Box<Pattern>) -> Self {
+        Self { kind: ErrorKind::PatFailed(pat), span: None }
+    }
+    /// Fell through a non-exhaustive match
+    pub fn MatchNonexhaustive() -> Self {
+        Self { kind: ErrorKind::MatchNonexhaustive, span: None }
+    }
+    /// Explicit panic
+    pub fn Panic(msg: String) -> Self {
+        Self { kind: ErrorKind::Panic(msg, 0), span: None }
+    }
+    /// Error produced by a Builtin
+    pub fn BuiltinError(msg: String) -> Self {
+        Self { kind: ErrorKind::BuiltinError(msg), span: None }
+    }
+}
+
+impl std::error::Error for Error {}
+impl std::fmt::Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { kind, span } = self;
+        if let Some(Span { head, tail }) = span {
+            write!(f, "{head}..{tail}: ")?;
+        }
+        write!(f, "{kind}")
+    }
+}
+
+/// Represents any error thrown by the [Environment](super::Environment)
+#[derive(Clone, Debug)]
+pub enum ErrorKind {
+    /// Propagate a Return value
+    Return(ConValue),
+    /// Propagate a Break value
+    Break(ConValue),
+    /// Break propagated across function bounds
+    BadBreak(ConValue),
+    /// Continue to the next iteration of a loop
+    Continue,
+    /// Underflowed the stack
+    StackUnderflow,
+    /// Overflowed the stack
+    StackOverflow(usize),
+    /// Exited the last scope
+    ScopeExit,
+    /// Type incompatibility
+    // TODO: store the type information in this error
+    TypeError,
+    /// In clause of For loop didn't yield a Range
+    NotIterable,
+    /// A value could not be indexed
+    NotIndexable,
+    /// An array index went out of bounds
+    OobIndex(usize, usize),
+    /// An expression is not assignable
+    NotAssignable,
+    /// A name was not defined in scope before being used
+    NotDefined(Sym),
+    /// A name was defined but not initialized
+    NotInitialized(Sym),
+    /// A value was called, but is not callable
+    NotCallable(ConValue),
+    /// A function was called with the wrong number of arguments
+    ArgNumber { want: usize, got: usize },
+    /// A pattern failed to match
+    PatFailed(Box<Pattern>),
+    /// Fell through a non-exhaustive match
+    MatchNonexhaustive,
+    /// Explicit panic
+    Panic(String, usize),
+    /// Error produced by a Builtin
+    BuiltinError(String),
+}
+
+impl std::error::Error for ErrorKind {}
+impl std::fmt::Display for ErrorKind {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            ErrorKind::Return(value) => write!(f, "return {value}"),
+            ErrorKind::Break(value) => write!(f, "break {value}"),
+            ErrorKind::BadBreak(value) => write!(f, "rogue break: {value}"),
+            ErrorKind::Continue => "continue".fmt(f),
+            ErrorKind::StackUnderflow => "Stack underflow".fmt(f),
+            ErrorKind::StackOverflow(id) => {
+                write!(f, "Attempt to access <{id}> resulted in stack overflow.")
+            }
+            ErrorKind::ScopeExit => "Exited the last scope. This is a logic bug.".fmt(f),
+            ErrorKind::TypeError => "Incompatible types".fmt(f),
+            ErrorKind::NotIterable => "`in` clause of `for` loop did not yield an iterable".fmt(f),
+            ErrorKind::NotIndexable => {
+                write!(f, "expression cannot be indexed")
+            }
+            ErrorKind::OobIndex(idx, len) => {
+                write!(f, "Index out of bounds: index was {idx}. but len is {len}")
+            }
+            ErrorKind::NotAssignable => {
+                write!(f, "expression is not assignable")
+            }
+            ErrorKind::NotDefined(value) => {
+                write!(f, "{value} not bound. Did you mean `let {value};`?")
+            }
+            ErrorKind::NotInitialized(value) => {
+                write!(f, "{value} bound, but not initialized")
+            }
+            ErrorKind::NotCallable(value) => {
+                write!(f, "{value} is not callable.")
+            }
+            ErrorKind::ArgNumber { want, got } => {
+                write!(
+                    f,
+                    "Expected {want} argument{}, got {got}",
+                    if *want == 1 { "" } else { "s" }
+                )
+            }
+            ErrorKind::PatFailed(pattern) => {
+                write!(f, "Failed to match pattern {pattern}")
+            }
+            ErrorKind::MatchNonexhaustive => {
+                write!(f, "Fell through a non-exhaustive match expression!")
+            }
+            ErrorKind::Panic(s, _depth) => write!(f, "Explicit panic: {s}"),
+            ErrorKind::BuiltinError(s) => write!(f, "{s}"),
+        }
+    }
+}

compiler/cl-interpret/src/function.rs

@@ -0,0 +1,83 @@
+//! Represents a block of code which lives inside the Interpreter
+
+use collect_upvars::collect_upvars;
+
+use crate::error::ErrorKind;
+
+use super::{Callable, ConValue, Environment, Error, IResult, Interpret, pattern};
+use cl_ast::{Function as FnDecl, Sym};
+use std::{
+    cell::{Ref, RefCell},
+    collections::HashMap,
+    rc::Rc,
+};
+
+pub mod collect_upvars;
+
+type Upvars = HashMap<Sym, ConValue>;
+
+/// Represents a block of code which persists inside the Interpreter
+#[derive(Clone, Debug)]
+pub struct Function {
+    /// Stores the contents of the function declaration
+    decl: Rc<FnDecl>,
+    /// Stores data from the enclosing scopes
+    upvars: RefCell<Upvars>,
+}
+
+impl Function {
+    pub fn new(decl: &FnDecl) -> Self {
+        // let upvars = collect_upvars(decl, env);
+        Self { decl: decl.clone().into(), upvars: Default::default() }
+    }
+    pub fn decl(&self) -> &FnDecl {
+        &self.decl
+    }
+    pub fn upvars(&self) -> Ref<'_, Upvars> {
+        self.upvars.borrow()
+    }
+    pub fn lift_upvars(&self, env: &Environment) {
+        let upvars = collect_upvars(&self.decl, env);
+        if let Ok(mut self_upvars) = self.upvars.try_borrow_mut() {
+            *self_upvars = upvars;
+        }
+    }
+}
+
+impl Callable for Function {
+    fn name(&self) -> Sym {
+        let FnDecl { name, .. } = *self.decl;
+        name
+    }
+    fn call(&self, env: &mut Environment, args: &[ConValue]) -> IResult<ConValue> {
+        let FnDecl { name, gens: _, bind, body, sign: _ } = &*self.decl;
+
+        // Check arg mapping
+        let Some(body) = body else {
+            return Err(Error::NotDefined(*name));
+        };
+
+        let upvars = self.upvars.take();
+        let mut env = env.with_frame("upvars", upvars);
+
+        // TODO: completely refactor data storage
+        let mut frame = env.frame("fn args");
+        for (name, value) in pattern::substitution(&frame, bind, ConValue::Tuple(args.into()))? {
+            frame.insert(name, value);
+        }
+        let res = body.interpret(&mut frame);
+        drop(frame);
+        if let Some(upvars) = env.pop_values() {
+            self.upvars.replace(upvars);
+        }
+        match res {
+            Err(Error { kind: ErrorKind::Return(value), .. }) => Ok(value),
+            Err(Error { kind: ErrorKind::Break(value), .. }) => Err(Error::BadBreak(value)),
+            Err(Error { kind: ErrorKind::Panic(msg, depth), span: Some(span) }) => {
+                println!("{depth:>4}: {name}{bind} at {}", span.head);
+                Err(Error { kind: ErrorKind::Panic(msg, depth + 1), span: None })
+            }
+            other => other,
+        }
+    }
+}

compiler/cl-interpret/src/function/collect_upvars.rs

@@ -0,0 +1,112 @@
+//! Collects the "Upvars" of a function at the point of its creation, allowing variable capture
+use crate::env::Environment;
+use cl_ast::{
+    Function, Let, Path, PathPart, Pattern, Sym,
+    ast_visitor::{visit::*, walk::Walk},
+};
+use std::collections::{HashMap, HashSet};
+
+pub fn collect_upvars(f: &Function, env: &Environment) -> super::Upvars {
+    CollectUpvars::new(env).visit(f).finish_copied()
+}
+
+#[derive(Clone, Debug)]
+pub struct CollectUpvars<'env> {
+    env: &'env Environment,
+    upvars: HashMap<Sym, usize>,
+    blacklist: HashSet<Sym>,
+}
+
+impl<'env> CollectUpvars<'env> {
+    pub fn new(env: &'env Environment) -> Self {
+        Self { upvars: HashMap::new(), blacklist: HashSet::new(), env }
+    }
+
+    pub fn finish(&mut self) -> HashMap<Sym, usize> {
+        std::mem::take(&mut self.upvars)
+    }
+
+    pub fn finish_copied(&mut self) -> super::Upvars {
+        let Self { env, upvars, blacklist: _ } = self;
+        std::mem::take(upvars)
+            .into_iter()
+            .filter_map(|(k, v)| env.get_id(v).cloned().map(|v| (k, v)))
+            .collect()
+    }
+
+    pub fn add_upvar(&mut self, name: &Sym) {
+        let Self { env, upvars, blacklist } = self;
+        if blacklist.contains(name) || upvars.contains_key(name) {
+            return;
+        }
+        if let Ok(place) = env.id_of(*name) {
+            upvars.insert(*name, place);
+        }
+    }
+
+    pub fn bind_name(&mut self, name: &Sym) {
+        self.blacklist.insert(*name);
+    }
+
+    pub fn scope(&mut self, f: impl Fn(&mut CollectUpvars<'env>)) {
+        let blacklist = self.blacklist.clone();
+
+        // visit the scope
+        f(self);
+
+        // restore the blacklist
+        self.blacklist = blacklist;
+    }
+}
+
+impl<'a> Visit<'a> for CollectUpvars<'_> {
+    fn visit_block(&mut self, b: &'a cl_ast::Block) {
+        self.scope(|cu| b.children(cu));
+    }
+
+    fn visit_let(&mut self, l: &'a cl_ast::Let) {
+        let Let { mutable, name, ty, init } = l;
+        self.visit_mutability(mutable);
+
+        ty.visit_in(self);
+        // visit the initializer, which may use the bound name
+        init.visit_in(self);
+        // a bound name can never be an upvar
+        self.visit_pattern(name);
+    }
+
+    fn visit_path(&mut self, p: &'a cl_ast::Path) {
+        // TODO: path resolution in environments
+        let Path { absolute: false, parts } = p else {
+            return;
+        };
+        let [PathPart::Ident(name)] = parts.as_slice() else {
+            return;
+        };
+        self.add_upvar(name);
+    }
+
+    fn visit_fielder(&mut self, f: &'a cl_ast::Fielder) {
+        let cl_ast::Fielder { name, init } = f;
+        if let Some(init) = init {
+            self.visit_expr(init);
+        } else {
+            self.add_upvar(name); // fielder without init grabs from env
+        }
+    }
+
+    fn visit_pattern(&mut self, value: &'a cl_ast::Pattern) {
+        match value {
+            Pattern::Name(name) => {
+                self.bind_name(name);
+            }
+            Pattern::RangeExc(_, _) | Pattern::RangeInc(_, _) => {}
+            _ => value.children(self),
+        }
+    }
+
+    fn visit_match_arm(&mut self, value: &'a cl_ast::MatchArm) {
+        // MatchArms bind variables with a very small local scope
+        self.scope(|cu| value.children(cu));
+    }
+}

compiler/cl-interpret/src/lib.rs

@@ -0,0 +1,671 @@
+//! Walks a Conlang AST, interpreting it as a program.
+#![warn(clippy::all)]
+#![feature(decl_macro)]
+
+use cl_ast::Sym;
+use convalue::ConValue;
+use env::Environment;
+use error::{Error, ErrorKind, IResult};
+use interpret::Interpret;
+
+/// Callable types can be called from within a Conlang program
+pub trait Callable {
+    /// Calls this [Callable] in the provided [Environment], with [ConValue] args  \
+    /// The Callable is responsible for checking the argument count and validating types
+    fn call(&self, interpreter: &mut Environment, args: &[ConValue]) -> IResult<ConValue>;
+    /// Returns the common name of this identifier.
+    fn name(&self) -> Sym;
+}
+
+pub mod convalue;
+
+pub mod interpret;
+
+pub mod function;
+
+pub mod constructor {
+    use cl_ast::Sym;
+
+    use crate::{
+        Callable,
+        convalue::ConValue,
+        env::Environment,
+        error::{Error, IResult},
+    };
+
+    #[derive(Clone, Copy, Debug)]
+    pub struct Constructor {
+        pub name: Sym,
+        pub arity: u32,
+    }
+
+    impl Callable for Constructor {
+        fn call(&self, _env: &mut Environment, args: &[ConValue]) -> IResult<ConValue> {
+            let &Self { name, arity } = self;
+            if arity as usize == args.len() {
+                Ok(ConValue::TupleStruct(name, Box::new(args.into())))
+            } else {
+                Err(Error::ArgNumber(arity as usize, args.len()))
+            }
+        }
+
+        fn name(&self) -> cl_ast::Sym {
+            "tuple-constructor".into()
+        }
+    }
+}
+
+pub mod closure;
+
+pub mod builtin;
+
+pub mod pattern;
+
+pub mod env;
+
+pub mod modules {
+    use crate::env::StackBinds;
+    use cl_ast::{PathPart, Sym};
+    use std::collections::HashMap;
+
+    /// Immutable object-oriented interface to a [ModuleTree]
+    #[derive(Clone, Copy, Debug)]
+    pub struct ModuleNode<'tree> {
+        tree: &'tree ModuleTree,
+        index: usize,
+    }
+
+    /// Mutable object-oriented interface to a [ModuleTree]
+    #[derive(Debug)]
+    pub struct ModuleNodeMut<'tree> {
+        tree: &'tree mut ModuleTree,
+        index: usize,
+    }
+
+    macro_rules! module_node_impl {
+        () => {
+            /// Gets the index from this node
+            pub fn index(self) -> usize {
+                self.index
+            }
+            /// Gets this node's parent
+            pub fn parent(self) -> Option<Self> {
+                let parent = self.tree.parent(self.index)?;
+                Some(Self { index: parent, ..self })
+            }
+            /// Gets the node's "encompassing Type"
+            pub fn selfty(self) -> Option<Self> {
+                let selfty = self.tree.selfty(self.index)?;
+                Some(Self { index: selfty, ..self })
+            }
+            /// Gets the child of this node with the given name
+            pub fn child(self, name: &Sym) -> Option<Self> {
+                let child = self.tree.child(self.index, name)?;
+                Some(Self { index: child, ..self })
+            }
+            /// Gets a stack value in this node with the given name
+            pub fn item(self, name: &Sym) -> Option<usize> {
+                self.tree.items(self.index)?.get(name).copied()
+            }
+            /// Returns true when this node represents type information
+            pub fn is_ty(self) -> Option<bool> {
+                self.tree.is_ty.get(self.index).copied()
+            }
+            /// Returns a reference to this node's children, if present
+            pub fn children(&self) -> Option<&HashMap<Sym, usize>> {
+                self.tree.children(self.index)
+            }
+            /// Returns a reference to this node's items, if present
+            pub fn items(&self) -> Option<&StackBinds> {
+                self.tree.items(self.index)
+            }
+            /// Traverses a path starting at this node
+            ///
+            /// Returns a new node, and the unconsumed path portion.
+            pub fn find(self, path: &[PathPart]) -> (Self, &[PathPart]) {
+                let (index, path) = self.tree.find(self.index, path);
+                (Self { index, ..self }, path)
+            }
+            /// Traverses a path starting at this node
+            ///
+            /// Returns an item address if the path terminated in an item.
+            pub fn find_item(&self, path: &[PathPart]) -> Option<usize> {
+                self.tree.find_item(self.index, path)
+            }
+        };
+    }
+
+    impl ModuleNode<'_> {
+        module_node_impl! {}
+    }
+
+    impl ModuleNodeMut<'_> {
+        module_node_impl! {}
+        /// Creates a new child in this node
+        pub fn add_child(self, name: Sym, is_ty: bool) -> Self {
+            let node = self.tree.add_child(self.index, name, is_ty);
+            self.tree.get_mut(node)
+        }
+        /// Creates an arbitrary edge in the module graph
+        pub fn add_import(&mut self, name: Sym, child: usize) {
+            self.tree.add_import(self.index, name, child)
+        }
+        pub fn add_imports(&mut self, binds: HashMap<Sym, usize>) {
+            self.tree.add_imports(self.index, binds)
+        }
+        /// Binds a new item in this node
+        pub fn add_item(&mut self, name: Sym, stack_index: usize) {
+            self.tree.add_item(self.index, name, stack_index)
+        }
+        /// Binds an entire stack frame in this node
+        pub fn add_items(&mut self, binds: StackBinds) {
+            self.tree.add_items(self.index, binds)
+        }
+        /// Constructs a borrowing [ModuleNode]
+        pub fn as_ref(&self) -> ModuleNode<'_> {
+            let Self { tree, index } = self;
+            ModuleNode { tree, index: *index }
+        }
+    }
+
+    #[derive(Clone, Debug)]
+    pub struct ModuleTree {
+        parents: Vec<usize>,
+        children: Vec<HashMap<Sym, usize>>,
+        items: Vec<StackBinds>,
+        is_ty: Vec<bool>,
+    }
+
+    impl ModuleTree {
+        /// Constructs a new ModuleTree with a single root module
+        pub fn new() -> Self {
+            Self {
+                parents: vec![0],
+                children: vec![HashMap::new()],
+                items: vec![HashMap::new()],
+                is_ty: vec![false],
+            }
+        }
+
+        /// Gets a borrowed handle to the node at `index`
+        pub fn get(&self, index: usize) -> ModuleNode<'_> {
+            ModuleNode { tree: self, index }
+        }
+
+        /// Gets a mutable handle to the node at `index`
+        pub fn get_mut(&mut self, index: usize) -> ModuleNodeMut<'_> {
+            ModuleNodeMut { tree: self, index }
+        }
+
+        /// Creates a new child in this node
+        pub fn add_child(&mut self, parent: usize, name: Sym, is_ty: bool) -> usize {
+            let index = self.parents.len();
+            self.children[parent].insert(name, index);
+            self.parents.push(parent);
+            self.children.push(HashMap::new());
+            self.is_ty.push(is_ty);
+            index
+        }
+
+        /// Binds a new item in this node
+        pub fn add_item(&mut self, node: usize, name: Sym, stack_index: usize) {
+            self.items[node].insert(name, stack_index);
+        }
+
+        /// Creates an arbitrary child edge
+        pub fn add_import(&mut self, parent: usize, name: Sym, child: usize) {
+            self.children[parent].insert(name, child);
+        }
+
+        /// Binds an entire stack frame in this node
+        pub fn add_items(&mut self, node: usize, binds: StackBinds) {
+            self.items[node].extend(binds);
+        }
+
+        /// Binds an arbitrary set of child edges
+        pub fn add_imports(&mut self, node: usize, binds: HashMap<Sym, usize>) {
+            self.children[node].extend(binds);
+        }
+
+        /// Gets this node's parent
+        pub fn parent(&self, node: usize) -> Option<usize> {
+            if node == 0 {
+                return None;
+            }
+            self.parents.get(node).copied()
+        }
+
+        /// Gets the node's "encompassing Type"
+        pub fn selfty(&self, node: usize) -> Option<usize> {
+            if self.is_ty[node] {
+                return Some(node);
+            }
+            self.selfty(self.parent(node)?)
+        }
+
+        /// Gets the child of this node with the given name
+        pub fn child(&self, node: usize, id: &Sym) -> Option<usize> {
+            self.children[node].get(id).copied()
+        }
+
+        /// Gets a stack value in this node with the given name
+        pub fn item(&self, node: usize, name: &Sym) -> Option<usize> {
+            self.items.get(node).and_then(|map| map.get(name).copied())
+        }
+
+        /// Returns a reference to this node's children, if present
+        pub fn children(&self, node: usize) -> Option<&HashMap<Sym, usize>> {
+            self.children.get(node)
+        }
+
+        /// Returns a reference to this node's items, if present
+        pub fn items(&self, node: usize) -> Option<&StackBinds> {
+            self.items.get(node)
+        }
+
+        /// Traverses a path starting at this node
+        ///
+        /// Returns a new node, and the unconsumed path portion.
+        pub fn find<'p>(&self, node: usize, path: &'p [PathPart]) -> (usize, &'p [PathPart]) {
+            match path {
+                [PathPart::SuperKw, tail @ ..] => match self.parent(node) {
+                    Some(node) => self.find(node, tail),
+                    None => (node, path),
+                },
+                [PathPart::Ident(name), tail @ ..] => match self.child(node, name) {
+                    Some(node) => self.find(node, tail),
+                    None => (node, path),
+                },
+                [PathPart::SelfTy, tail @ ..] => match self.selfty(node) {
+                    Some(node) => self.find(node, tail),
+                    None => (node, path),
+                },
+                [] => (node, path),
+            }
+        }
+
+        /// Traverses a path starting at this node
+        ///
+        /// Returns an item address if the path terminated in an item.
+        pub fn find_item(&self, node: usize, path: &[PathPart]) -> Option<usize> {
+            let (node, [PathPart::Ident(name)]) = self.find(node, path) else {
+                return None;
+            };
+            self.item(node, name)
+        }
+    }
+
+    impl Default for ModuleTree {
+        fn default() -> Self {
+            Self::new()
+        }
+    }
+}
+
+pub mod collector {
+    use std::ops::{Deref, DerefMut};
+
+    use crate::{
+        convalue::ConValue,
+        env::Environment,
+        modules::{ModuleNode, ModuleNodeMut},
+    };
+    use cl_ast::{
+        ast_visitor::{Visit, Walk},
+        *,
+    };
+
+    pub struct Collector<'env> {
+        module: usize,
+        env: &'env mut Environment,
+    }
+
+    impl Collector<'_> {
+        pub fn as_node(&self) -> ModuleNode<'_> {
+            self.env.modules().get(self.module)
+        }
+
+        pub fn as_node_mut(&mut self) -> ModuleNodeMut<'_> {
+            self.env.modules_mut().get_mut(self.module)
+        }
+
+        pub fn scope(&mut self, name: Sym, is_ty: bool, f: impl Fn(&mut Collector<'_>)) {
+            let module = match self.as_node_mut().child(&name) {
+                Some(m) => m,
+                None => self.as_node_mut().add_child(name, is_ty),
+            }
+            .index();
+
+            let mut frame = self.env.frame(name.to_ref());
+            f(&mut Collector { env: &mut frame, module });
+            let binds = frame.into_binds().unwrap_or_default();
+
+            self.modules_mut().add_items(module, binds);
+        }
+
+        pub fn in_foreign_scope<F, T>(&mut self, path: &[PathPart], f: F) -> Option<T>
+        where F: Fn(&mut Collector<'_>) -> T {
+            let (module, []) = self.env.modules_mut().find(self.module, path) else {
+                return None;
+            };
+
+            let mut frame = self.env.frame("impl");
+            let out = f(&mut Collector { env: &mut frame, module });
+            let binds = frame.into_binds().unwrap_or_default();
+
+            self.env.modules_mut().add_items(module, binds);
+            Some(out)
+        }
+    }
+
+    impl<'env> Deref for Collector<'env> {
+        type Target = Environment;
+        fn deref(&self) -> &Self::Target {
+            self.env
+        }
+    }
+
+    impl DerefMut for Collector<'_> {
+        fn deref_mut(&mut self) -> &mut Self::Target {
+            self.env
+        }
+    }
+
+    impl<'a, 'env> Visit<'a> for Collector<'env> {
+        fn visit_file(&mut self, value: &'a File) {
+            let mut sorter = ItemSorter::default();
+            sorter.visit(value);
+            sorter.visit_all(self);
+        }
+        fn visit_block(&mut self, value: &'a Block) {
+            let mut sorter = ItemSorter::default();
+            sorter.visit(value);
+            sorter.visit_all(self);
+        }
+        fn visit_module(&mut self, value: &'a cl_ast::Module) {
+            self.scope(value.name, false, |scope| value.children(scope));
+        }
+        fn visit_alias(&mut self, value: &'a cl_ast::Alias) {
+            let Alias { name, from } = value;
+            match from.as_ref().map(Box::as_ref) {
+                Some(Ty { kind: TyKind::Path(path), .. }) => {
+                    let mut node = if path.absolute {
+                        self.modules_mut().get_mut(0)
+                    } else {
+                        self.as_node_mut()
+                    };
+                    if let Some(item) = node.find_item(&path.parts) {
+                        node.add_item(*name, item);
+                    }
+                }
+                Some(other) => todo!("Type expressions in the collector: {other}"),
+                None => self.scope(*name, true, |_| {}),
+            }
+        }
+        fn visit_enum(&mut self, value: &'a cl_ast::Enum) {
+            let Enum { name, gens: _, variants } = value;
+
+            self.scope(*name, true, |frame| {
+                for (idx, Variant { name, kind, body }) in variants.iter().enumerate() {
+                    frame.visit(body);
+                    frame.scope(*name, false, |frame| {
+                        frame.bind("__discriminant", idx as isize);
+                        match kind {
+                            StructKind::Empty => {
+                                frame.insert_tup_constructor("call".into(), 0);
+                                frame.bind("__nmemb", ConValue::Int(0));
+                            }
+                            StructKind::Tuple(args) => {
+                                // Constructs the AST from scratch. TODO: This, better.
+                                frame.insert_tup_constructor("call".into(), args.len());
+                                frame.bind("__nmemb", ConValue::Int(args.len() as _));
+                            }
+                            StructKind::Struct(members) => {
+                                // TODO: more precise type checking of structs
+                                for (idx, memb) in members.iter().enumerate() {
+                                    let StructMember { vis: _, name, ty: _ } = memb;
+                                    frame.bind(*name, idx as isize);
+                                }
+                                frame.bind("__nmemb", ConValue::Int(members.len() as _));
+                            }
+                        }
+                    });
+                }
+            });
+        }
+        fn visit_struct(&mut self, value: &'a cl_ast::Struct) {
+            let Struct { name, gens: _, kind } = value;
+
+            self.scope(*name, true, |frame| {
+                match kind {
+                    StructKind::Empty => {
+                        frame.insert_tup_constructor("call".into(), 0);
+                        frame.bind("__nmemb", ConValue::Int(0));
+                    }
+                    StructKind::Tuple(args) => {
+                        // Constructs the AST from scratch. TODO: This, better.
+                        frame.insert_tup_constructor("call".into(), args.len());
+                        frame.bind("__nmemb", ConValue::Int(args.len() as _));
+                    }
+                    StructKind::Struct(members) => {
+                        // TODO: more precise type checking of structs
+                        for (idx, memb) in members.iter().enumerate() {
+                            let StructMember { vis: _, name, ty: _ } = memb;
+                            frame.bind(*name, idx as isize);
+                        }
+                        frame.bind("__nmemb", ConValue::Int(members.len() as _));
+                    }
+                }
+            });
+        }
+        fn visit_const(&mut self, value: &'a cl_ast::Const) {
+            let Const { name, ty: _, init } = value;
+            self.visit(init);
+            self.bind(*name, ());
+        }
+        fn visit_static(&mut self, value: &'a cl_ast::Static) {
+            let Static { mutable: _, name, ty: _, init } = value;
+            self.visit(init);
+            self.bind(*name, ());
+        }
+        fn visit_function(&mut self, value: &'a cl_ast::Function) {
+            let Function { name, gens: _, sign: _, bind: _, body } = value;
+            self.scope(*name, false, |scope| {
+                scope.visit(body);
+                let f = crate::function::Function::new(value);
+                scope.bind("call", f);
+            });
+        }
+        fn visit_impl(&mut self, value: &'a cl_ast::Impl) {
+            let Impl { gens: _, target: ImplKind::Type(Ty { kind: TyKind::Path(name), .. }), body } =
+                value
+            else {
+                eprintln!("TODO: impl X for Ty");
+                return;
+            };
+            self.in_foreign_scope(&name.parts, |scope| {
+                body.visit_in(scope);
+            });
+        }
+        fn visit_use(&mut self, value: &'a cl_ast::Use) {
+            fn traverse(dest: &mut Collector<'_>, node: usize, tree: &UseTree) {
+                match tree {
+                    UseTree::Tree(ts) => ts.iter().for_each(|tree| traverse(dest, node, tree)),
+                    UseTree::Path(PathPart::Ident(name), tree) => {
+                        if let (node, []) = dest.modules().find(node, &[PathPart::Ident(*name)]) {
+                            traverse(dest, node, tree)
+                        }
+                    }
+                    UseTree::Path(PathPart::SuperKw, tree) => {
+                        if let Some(node) = dest.modules().parent(node) {
+                            traverse(dest, node, tree)
+                        }
+                    }
+                    UseTree::Path(PathPart::SelfTy, tree) => {
+                        if let Some(node) = dest.modules().selfty(node) {
+                            traverse(dest, node, tree)
+                        }
+                    }
+                    UseTree::Alias(name, as_name) => {
+                        if let Some(child) = dest.modules().child(node, name) {
+                            dest.as_node_mut().add_import(*as_name, child);
+                        }
+                        if let Some(item) = dest.modules().item(node, name) {
+                            dest.as_node_mut().add_item(*as_name, item);
+                        }
+                    }
+                    UseTree::Name(name) => {
+                        if let Some(child) = dest.modules().child(node, name) {
+                            dest.as_node_mut().add_import(*name, child);
+                        }
+                        if let Some(item) = dest.modules().item(node, name) {
+                            dest.as_node_mut().add_item(*name, item);
+                        }
+                    }
+                    UseTree::Glob => {
+                        let &mut Collector { module, ref mut env } = dest;
+                        if let Some(children) = env.modules().children(node) {
+                            for (name, index) in children.clone() {
+                                env.modules_mut().add_import(module, name, index);
+                            }
+                        }
+                        if let Some(items) = env.modules().items(node).cloned() {
+                            env.modules_mut().add_items(node, items);
+                        }
+                    }
+                }
+            }
+
+            let Use { absolute, tree } = value;
+            let node = if *absolute { 0 } else { self.module };
+            traverse(self, node, tree);
+        }
+    }
+
+    // fn make_tuple_constructor(name: Sym, args: &[Ty]) -> ConValue {
+    //     let span = match (
+    //         args.first().map(|a| a.span.head),
+    //         args.last().map(|a| a.span.tail),
+    //     ) {
+    //         (Some(head), Some(tail)) => Span(head, tail),
+    //         _ => Span::dummy(),
+    //     };
+
+    //     let constructor = Function {
+    //         name,
+    //         gens: Default::default(),
+    //         sign: TyFn {
+    //             args: Ty { kind: TyKind::Tuple(TyTuple { types: args.to_vec() }), span }.into(),
+    //             rety: Some(Ty { span: Span::dummy(), kind: TyKind::Path(Path::from(name))
+    // }.into()),         },
+    //         bind: Pattern::Tuple(
+    //             args.iter()
+    //                 .enumerate()
+    //                 .map(|(idx, _)| Pattern::Name(idx.to_string().into()))
+    //                 .collect(),
+    //         ),
+    //         body: None,
+    //     };
+    //     // ConValue::TupleConstructor(crate::constructor::Constructor {ind})
+    //     todo!("Tuple constructor {constructor}")
+    // }
+
+    /// Sorts items
+    #[derive(Debug, Default)]
+    struct ItemSorter<'ast> {
+        modules: Vec<&'ast Module>,
+        structs: Vec<&'ast Struct>,
+        enums: Vec<&'ast Enum>,
+        aliases: Vec<&'ast Alias>,
+        consts: Vec<&'ast Const>,
+        statics: Vec<&'ast Static>,
+        functions: Vec<&'ast Function>,
+        impls: Vec<&'ast Impl>,
+        imports: Vec<&'ast Use>,
+    }
+
+    impl<'a> ItemSorter<'a> {
+        fn visit_all<V: Visit<'a>>(&self, v: &mut V) {
+            let Self {
+                modules,
+                aliases,
+                enums,
+                structs,
+                consts,
+                statics,
+                functions,
+                impls,
+                imports,
+            } = self;
+
+            // 0
+            for item in modules {
+                item.visit_in(v);
+            }
+            // 1
+            for item in structs {
+                item.visit_in(v);
+            }
+            for item in enums {
+                item.visit_in(v);
+            }
+            for item in aliases {
+                item.visit_in(v);
+            }
+            // 2
+            // 5
+            for item in consts {
+                item.visit_in(v);
+            }
+            for item in statics {
+                item.visit_in(v);
+            }
+            for item in functions {
+                item.visit_in(v);
+            }
+            // 4
+            for item in impls {
+                item.visit_in(v);
+            }
+            // 3
+            for item in imports {
+                item.visit_in(v);
+            }
+        }
+    }
+
+    impl<'a> Visit<'a> for ItemSorter<'a> {
+        fn visit_module(&mut self, value: &'a cl_ast::Module) {
+            self.modules.push(value);
+        }
+        fn visit_alias(&mut self, value: &'a cl_ast::Alias) {
+            self.aliases.push(value);
+        }
+        fn visit_enum(&mut self, value: &'a cl_ast::Enum) {
+            self.enums.push(value);
+        }
+        fn visit_struct(&mut self, value: &'a cl_ast::Struct) {
+            self.structs.push(value);
+        }
+        fn visit_const(&mut self, value: &'a cl_ast::Const) {
+            self.consts.push(value);
+        }
+        fn visit_static(&mut self, value: &'a cl_ast::Static) {
+            self.statics.push(value);
+        }
+        fn visit_function(&mut self, value: &'a cl_ast::Function) {
+            self.functions.push(value);
+        }
+        fn visit_impl(&mut self, value: &'a cl_ast::Impl) {
+            self.impls.push(value);
+        }
+        fn visit_use(&mut self, value: &'a cl_ast::Use) {
+            self.imports.push(value);
+        }
+    }
+}
+
+pub mod error;
+
+#[cfg(test)]
+mod tests;

compiler/cl-interpret/src/pattern.rs

@@ -0,0 +1,347 @@
+//! Unification algorithm for cl-ast [Pattern]s and [ConValue]s
+//!
+//! [`variables()`] returns a flat list of symbols that are bound by a given pattern
+//! [`substitution()`] unifies a ConValue with a pattern, and produces a list of bound names
+
+use crate::{
+    convalue::ConValue,
+    env::Environment,
+    error::{Error, IResult},
+};
+use cl_ast::{Literal, Pattern, Sym};
+use std::collections::{HashMap, VecDeque};
+
+/// Gets the path variables in the given Pattern
+pub fn variables(pat: &Pattern) -> Vec<&Sym> {
+    fn patvars<'p>(set: &mut Vec<&'p Sym>, pat: &'p Pattern) {
+        match pat {
+            Pattern::Name(name) if name.to_ref() == "_" => {}
+            Pattern::Name(name) => set.push(name),
+            Pattern::Path(_) => {}
+            Pattern::Literal(_) => {}
+            Pattern::Rest(Some(pattern)) => patvars(set, pattern),
+            Pattern::Rest(None) => {}
+            Pattern::Ref(_, pattern) => patvars(set, pattern),
+            Pattern::RangeExc(_, _) => {}
+            Pattern::RangeInc(_, _) => {}
+            Pattern::Tuple(patterns) | Pattern::Array(patterns) => {
+                patterns.iter().for_each(|pat| patvars(set, pat))
+            }
+            Pattern::Struct(_path, items) => {
+                items.iter().for_each(|(name, pat)| match pat {
+                    Some(pat) => patvars(set, pat),
+                    None => set.push(name),
+                });
+            }
+            Pattern::TupleStruct(_path, items) => {
+                items.iter().for_each(|pat| patvars(set, pat));
+            }
+        }
+    }
+    let mut set = Vec::new();
+    patvars(&mut set, pat);
+    set
+}
+
+fn rest_binding<'pat>(
+    env: &Environment,
+    sub: &mut HashMap<Sym, ConValue>,
+    mut patterns: &'pat [Pattern],
+    mut values: VecDeque<ConValue>,
+) -> IResult<Option<(&'pat Pattern, VecDeque<ConValue>)>> {
+    // Bind the head of the list
+    while let [pattern, tail @ ..] = patterns {
+        if matches!(pattern, Pattern::Rest(_)) {
+            break;
+        }
+        let value = values
+            .pop_front()
+            .ok_or_else(|| Error::PatFailed(Box::new(pattern.clone())))?;
+        append_sub(env, sub, pattern, value)?;
+        patterns = tail;
+    }
+    // Bind the tail of the list
+    while let [head @ .., pattern] = patterns {
+        if matches!(pattern, Pattern::Rest(_)) {
+            break;
+        }
+        let value = values
+            .pop_back()
+            .ok_or_else(|| Error::PatFailed(Box::new(pattern.clone())))?;
+        append_sub(env, sub, pattern, value)?;
+        patterns = head;
+    }
+    // Bind the ..rest of the list
+    match patterns {
+        [] | [Pattern::Rest(None)] => Ok(None),
+        [Pattern::Rest(Some(pattern))] => Ok(Some((pattern.as_ref(), values))),
+        _ => Err(Error::PatFailed(Box::new(Pattern::Array(patterns.into())))),
+    }
+}
+
+fn rest_binding_ref<'pat>(
+    env: &Environment,
+    sub: &mut HashMap<Sym, ConValue>,
+    mut patterns: &'pat [Pattern],
+    mut head: usize,
+    mut tail: usize,
+) -> IResult<Option<(&'pat Pattern, usize, usize)>> {
+    // Bind the head of the list
+    while let [pattern, pat_tail @ ..] = patterns {
+        if matches!(pattern, Pattern::Rest(_)) {
+            break;
+        }
+        if head >= tail {
+            return Err(Error::PatFailed(Box::new(pattern.clone())));
+        }
+
+        append_sub(env, sub, pattern, ConValue::Ref(head))?;
+        head += 1;
+        patterns = pat_tail;
+    }
+    // Bind the tail of the list
+    while let [pat_head @ .., pattern] = patterns {
+        if matches!(pattern, Pattern::Rest(_)) {
+            break;
+        }
+        if head >= tail {
+            return Err(Error::PatFailed(Box::new(pattern.clone())));
+        };
+        append_sub(env, sub, pattern, ConValue::Ref(tail))?;
+        tail -= 1;
+        patterns = pat_head;
+    }
+    // Bind the ..rest of the list
+    match (patterns, tail - head) {
+        ([], 0) | ([Pattern::Rest(None)], _) => Ok(None),
+        ([Pattern::Rest(Some(pattern))], _) => Ok(Some((pattern.as_ref(), head, tail))),
+        _ => Err(Error::PatFailed(Box::new(Pattern::Array(patterns.into())))),
+    }
+}
+
+/// Appends a substitution to the provided table
+pub fn append_sub(
+    env: &Environment,
+    sub: &mut HashMap<Sym, ConValue>,
+    pat: &Pattern,
+    value: ConValue,
+) -> IResult<()> {
+    match (pat, value) {
+        (Pattern::Literal(Literal::Bool(a)), ConValue::Bool(b)) => {
+            (*a == b).then_some(()).ok_or(Error::NotAssignable())
+        }
+        (Pattern::Literal(Literal::Char(a)), ConValue::Char(b)) => {
+            (*a == b).then_some(()).ok_or(Error::NotAssignable())
+        }
+        (Pattern::Literal(Literal::Float(a)), ConValue::Float(b)) => (f64::from_bits(*a) == b)
+            .then_some(())
+            .ok_or(Error::NotAssignable()),
+        (Pattern::Literal(Literal::Int(a)), ConValue::Int(b)) => {
+            (b == *a as _).then_some(()).ok_or(Error::NotAssignable())
+        }
+        (Pattern::Literal(Literal::String(a)), ConValue::Str(b)) => {
+            (*a == *b).then_some(()).ok_or(Error::NotAssignable())
+        }
+        (Pattern::Literal(Literal::String(a)), ConValue::String(b)) => {
+            (*a == *b).then_some(()).ok_or(Error::NotAssignable())
+        }
+        (Pattern::Literal(_), _) => Err(Error::NotAssignable()),
+
+        (Pattern::Rest(Some(pat)), value) => match (pat.as_ref(), value) {
+            (Pattern::Literal(Literal::Int(a)), ConValue::Int(b)) => {
+                (b < *a as _).then_some(()).ok_or(Error::NotAssignable())
+            }
+            (Pattern::Literal(Literal::Char(a)), ConValue::Char(b)) => {
+                (b < *a as _).then_some(()).ok_or(Error::NotAssignable())
+            }
+            (Pattern::Literal(Literal::Bool(a)), ConValue::Bool(b)) => {
+                (!b & *a).then_some(()).ok_or(Error::NotAssignable())
+            }
+            (Pattern::Literal(Literal::Float(a)), ConValue::Float(b)) => {
+                (b < *a as _).then_some(()).ok_or(Error::NotAssignable())
+            }
+            (Pattern::Literal(Literal::String(a)), ConValue::Str(b)) => {
+                (&*b < a).then_some(()).ok_or(Error::NotAssignable())
+            }
+            (Pattern::Literal(Literal::String(a)), ConValue::String(b)) => {
+                (&*b < a).then_some(()).ok_or(Error::NotAssignable())
+            }
+            _ => Err(Error::NotAssignable()),
+        },
+
+        (Pattern::Name(name), _) if "_".eq(&**name) => Ok(()),
+        (Pattern::Name(name), value) => {
+            sub.insert(*name, value);
+            Ok(())
+        }
+
+        (Pattern::Ref(_, pat), ConValue::Ref(r)) => match env.get_id(r) {
+            Some(value) => append_sub(env, sub, pat, value.clone()),
+            None => Err(Error::PatFailed(pat.clone())),
+        },
+
+        (Pattern::Ref(_, pat), ConValue::Slice(head, len)) => {
+            let mut values = Vec::with_capacity(len);
+            for idx in head..(head + len) {
+                values.push(env.get_id(idx).cloned().ok_or(Error::StackOverflow(idx))?);
+            }
+            append_sub(env, sub, pat, ConValue::Array(values.into_boxed_slice()))
+        }
+
+        (Pattern::RangeExc(head, tail), value) => match (head.as_ref(), tail.as_ref(), value) {
+            (
+                Pattern::Literal(Literal::Int(a)),
+                Pattern::Literal(Literal::Int(c)),
+                ConValue::Int(b),
+            ) => (*a as isize <= b as _ && b < *c as isize)
+                .then_some(())
+                .ok_or(Error::NotAssignable()),
+            (
+                Pattern::Literal(Literal::Char(a)),
+                Pattern::Literal(Literal::Char(c)),
+                ConValue::Char(b),
+            ) => (*a <= b && b < *c)
+                .then_some(())
+                .ok_or(Error::NotAssignable()),
+            (
+                Pattern::Literal(Literal::Float(a)),
+                Pattern::Literal(Literal::Float(c)),
+                ConValue::Float(b),
+            ) => (f64::from_bits(*a) <= b && b < f64::from_bits(*c))
+                .then_some(())
+                .ok_or(Error::NotAssignable()),
+            (
+                Pattern::Literal(Literal::String(a)),
+                Pattern::Literal(Literal::String(c)),
+                ConValue::Str(b),
+            ) => (a.as_str() <= b.to_ref() && b.to_ref() < c.as_str())
+                .then_some(())
+                .ok_or(Error::NotAssignable()),
+            (
+                Pattern::Literal(Literal::String(a)),
+                Pattern::Literal(Literal::String(c)),
+                ConValue::String(b),
+            ) => (a.as_str() <= b.as_str() && b.as_str() < c.as_str())
+                .then_some(())
+                .ok_or(Error::NotAssignable()),
+            _ => Err(Error::NotAssignable()),
+        },
+
+        (Pattern::RangeInc(head, tail), value) => match (head.as_ref(), tail.as_ref(), value) {
+            (
+                Pattern::Literal(Literal::Int(a)),
+                Pattern::Literal(Literal::Int(c)),
+                ConValue::Int(b),
+            ) => (*a as isize <= b && b <= *c as isize)
+                .then_some(())
+                .ok_or(Error::NotAssignable()),
+            (
+                Pattern::Literal(Literal::Char(a)),
+                Pattern::Literal(Literal::Char(c)),
+                ConValue::Char(b),
+            ) => (*a <= b && b <= *c)
+                .then_some(())
+                .ok_or(Error::NotAssignable()),
+            (
+                Pattern::Literal(Literal::Float(a)),
+                Pattern::Literal(Literal::Float(c)),
+                ConValue::Float(b),
+            ) => (f64::from_bits(*a) <= b && b <= f64::from_bits(*c))
+                .then_some(())
+                .ok_or(Error::NotAssignable()),
+            (
+                Pattern::Literal(Literal::String(a)),
+                Pattern::Literal(Literal::String(c)),
+                ConValue::Str(b),
+            ) => (a.as_str() <= b.to_ref() && b.to_ref() <= c.as_str())
+                .then_some(())
+                .ok_or(Error::NotAssignable()),
+            (
+                Pattern::Literal(Literal::String(a)),
+                Pattern::Literal(Literal::String(c)),
+                ConValue::String(b),
+            ) => (a.as_str() <= b.as_str() && b.as_str() <= c.as_str())
+                .then_some(())
+                .ok_or(Error::NotAssignable()),
+            _ => Err(Error::NotAssignable()),
+        },
+
+        (Pattern::Array(patterns), ConValue::Array(values)) => {
+            match rest_binding(env, sub, patterns, values.into_vec().into())? {
+                Some((pattern, values)) => {
+                    append_sub(env, sub, pattern, ConValue::Array(Vec::from(values).into()))
+                }
+                _ => Ok(()),
+            }
+        }
+
+        (Pattern::Array(patterns), ConValue::Slice(head, len)) => {
+            match rest_binding_ref(env, sub, patterns, head, head + len)? {
+                Some((pat, head, tail)) => {
+                    append_sub(env, sub, pat, ConValue::Slice(head, tail - head))
+                }
+                None => Ok(()),
+            }
+        }
+
+        (Pattern::Tuple(patterns), ConValue::Empty) if patterns.is_empty() => Ok(()),
+        (Pattern::Tuple(patterns), ConValue::Tuple(values)) => {
+            match rest_binding(env, sub, patterns, values.into_vec().into())? {
+                Some((pattern, values)) => {
+                    append_sub(env, sub, pattern, ConValue::Tuple(Vec::from(values).into()))
+                }
+                _ => Ok(()),
+            }
+        }
+
+        (Pattern::TupleStruct(path, patterns), ConValue::TupleStruct(id, values)) => {
+            let tid = path
+                .as_sym()
+                .ok_or_else(|| Error::PatFailed(pat.clone().into()))?;
+            if id != tid {
+                return Err(Error::PatFailed(pat.clone().into()));
+            }
+            match rest_binding(env, sub, patterns, values.into_vec().into())? {
+                Some((pattern, values)) => {
+                    append_sub(env, sub, pattern, ConValue::Tuple(Vec::from(values).into()))
+                }
+                _ => Ok(()),
+            }
+        }
+
+        (Pattern::Struct(path, patterns), ConValue::Struct(id, mut values)) => {
+            let tid = path
+                .as_sym()
+                .ok_or_else(|| Error::PatFailed(pat.clone().into()))?;
+            if id != tid {
+                return Err(Error::PatFailed(pat.clone().into()));
+            }
+            for (name, pat) in patterns {
+                let value = values.remove(name).ok_or(Error::TypeError())?;
+                match pat {
+                    Some(pat) => append_sub(env, sub, pat, value)?,
+                    None => {
+                        sub.insert(*name, value);
+                    }
+                }
+            }
+            Ok(())
+        }
+
+        _ => {
+            // eprintln!("Could not match pattern `{pat}` with value `{value}`!");
+            Err(Error::NotAssignable())
+        }
+    }
+}
+
+/// Constructs a substitution from a pattern and a value
+pub fn substitution(
+    env: &Environment,
+    pat: &Pattern,
+    value: ConValue,
+) -> IResult<HashMap<Sym, ConValue>> {
+    let mut sub = HashMap::new();
+    append_sub(env, &mut sub, pat, value)?;
+    Ok(sub)
+}

compiler/cl-interpret/src/tests.rs

@@ -1,5 +1,5 @@
 #![allow(unused_imports)]
-use crate::{env::Environment, temp_type_impl::ConValue, Interpret};
+use crate::{Interpret, convalue::ConValue, env::Environment};
 use cl_ast::*;
 use cl_lexer::Lexer;
 use cl_parser::Parser;
@@ -48,6 +48,7 @@ mod macros {
     //! ```
     #![allow(unused_macros)]
     use crate::IResult;
+    use cl_parser::parser::Parse;
 
     use super::*;
 
@@ -63,14 +64,14 @@ mod macros {
     ///
     /// Returns a `Result<`[`File`]`, ParseError>`
     pub macro file($($t:tt)*) {
-        Parser::new(Lexer::new(stringify!( $($t)* ))).file()
+        File::parse(&mut Parser::new(Lexer::new(stringify!( $($t)* ))))
     }
 
     /// Stringifies, lexes, and parses everything you give to it
     ///
     /// Returns a `Result<`[`Block`]`, ParseError>`
     pub macro block($($t:tt)*) {
-        Parser::new(Lexer::new(stringify!({ $($t)* }))).block()
+        Block::parse(&mut Parser::new("test", Lexer::new(stringify!({ $($t)* }))))
     }
 
     /// Evaluates a block of code in the given environment
@@ -127,7 +128,7 @@ mod macros {
     }
 
     pub macro env_ne($env:ident.$var:ident, $expr:expr) {{
-        let evaluated = $env.get(stringify!($var))
+        let evaluated = $env.get(stringify!($var).into())
             .expect(stringify!($var should be defined and initialized));
         if !conv_cmp!(neq, evaluated, $expr) {
             panic!("assertion {} ({evaluated}) != {} failed.", stringify!($var), stringify!($expr))
@@ -135,7 +136,7 @@ mod macros {
     }}
 
     pub macro env_eq($env:ident.$var:ident, $expr:expr) {{
-        let evaluated = $env.get(stringify!($var))
+        let evaluated = $env.get(stringify!($var).into())
             .expect(stringify!($var should be defined and initialized));
         if !conv_cmp!(eq, evaluated, $expr) {
             panic!("assertion {} ({evaluated}) == {} failed.", stringify!($var), stringify!($expr))
@@ -177,6 +178,45 @@ mod let_declarations {
         env_eq!(env.x, 10);
         env_eq!(env.y, 10);
     }
+
+    #[test]
+    fn let_destructuring_tuple() {
+        let mut env = Environment::new();
+        assert_eval!(env,
+            let (x, y) = (10, 20);
+        );
+
+        env_eq!(env.x, 10);
+        env_eq!(env.y, 20);
+    }
+
+    #[test]
+    fn let_destructuring_array() {
+        let mut env = Environment::new();
+        assert_eval!(env,
+            let [x, y] = [10, 20];
+        );
+
+        env_eq!(env.x, 10);
+        env_eq!(env.y, 20);
+    }
+
+    #[test]
+    fn let_destructuring_nested() {
+        let mut env = Environment::new();
+        assert_eval!(env,
+            let (x, [one, two, three], (a, b, c))
+              = ('x', [1, 2, 3], ('a', 'b', 'c'));
+        );
+
+        env_eq!(env.x, 'x');
+        env_eq!(env.one, 1);
+        env_eq!(env.two, 2);
+        env_eq!(env.three, 3);
+        env_eq!(env.a, 'a');
+        env_eq!(env.b, 'b');
+        env_eq!(env.c, 'c');
+    }
 }
 
 mod fn_declarations {
@@ -187,10 +227,10 @@ mod fn_declarations {
         assert_eval!(env, fn empty_fn() {});
         // TODO: true equality for functions
         assert_eq!(
-            "fn empty_fn () {\n    \n}",
+            "fn empty_fn () {}",
             format!(
                 "{}",
-                env.get("empty_fn")
+                env.get("empty_fn".into())
                     .expect(stringify!(empty_fn should be defined and initialized))
             )
         )
@@ -363,7 +403,7 @@ mod operators {
         env_eq!(env.is_10_ne_20, true); //  !=
         env_eq!(env.is_10_ge_20, false); // >=
         env_eq!(env.is_10_gt_20, false); // >
-                                         // Equal to
+        // Equal to
         env_eq!(env.is_10_lt_10, false);
         env_eq!(env.is_10_le_10, true);
         env_eq!(env.is_10_eq_10, true);
@@ -436,16 +476,17 @@ mod operators {
         env_eq!(env.y, 10);
         env_eq!(env.z, 10);
     }
-    #[test]
-    #[should_panic]
-    fn assignment_accounts_for_type() {
-        let mut env = Default::default();
-        assert_eval!(env,
-            let x = "a string";
-            let y = 0xdeadbeef;
-            y = x; // should crash: type error
-        );
-    }
+    // Test is disabled, since new assignment system intentionally does not care.
+    // #[test]
+    // #[should_panic]
+    // fn assignment_accounts_for_type() {
+    //     let mut env = Default::default();
+    //     assert_eval!(env,
+    //         let x = "a string";
+    //         let y = 0xdeadbeef;
+    //         y = x; // should crash: type error
+    //     );
+    // }
     #[test]
     fn precedence() {
         let mut env = Default::default();
@@ -468,6 +509,75 @@ mod operators {
     }
 }
 
+mod control_flow {
+    use super::*;
+
+    #[test]
+    fn if_evaluates_pass_block_on_true() {
+        let mut env = Default::default();
+        assert_eval!(env,
+            let evaluated = if true { "pass" } else { "fail" }
+        );
+        env_eq!(env.evaluated, "pass");
+    }
+
+    #[test]
+    fn if_evaluates_fail_block_on_false() {
+        let mut env = Default::default();
+        assert_eval!(env,
+            let evaluated = if false { "pass" } else { "fail" }
+        );
+        env_eq!(env.evaluated, "fail");
+    }
+
+    #[test]
+    fn while_evaluates_fail_block_on_false() {
+        let mut env = Default::default();
+        assert_eval!(env,
+            let cond = true;
+            let evaluated = while cond { cond = false } else { true }
+        );
+        env_eq!(env.evaluated, true);
+    }
+
+    #[test]
+    fn while_does_not_evaluate_fail_block_on_break() {
+        let mut env = Default::default();
+        assert_eval!(env,
+            let evaluated = while true { break true } else { false }
+        );
+        env_eq!(env.evaluated, true);
+    }
+
+    #[test]
+    fn match_evaluates_in_order() {
+        let mut env = Default::default();
+        assert_eval!(env,
+            let x = '\u{1f988}';
+            let passed = match x {
+                '\u{1f988}' => true,
+                _ => false,
+            };
+        );
+        env_eq!(env.passed, true);
+    }
+
+    #[test]
+    fn match_sinkoles_underscore_patterns() {
+        let mut env = Default::default();
+        assert_eval!(env,
+            let x = '\u{1f988}';
+            let passed = match x {
+                _ => true,
+                '\u{1f988}' => false,
+            };
+        );
+        env_eq!(env.passed, true);
+    }
+
+    //TODO: test other control flow constructs like loops, while-else, etc.
+}
+
 #[allow(dead_code)]
 fn test_template() {
     let mut env = Default::default();

compiler/cl-lexer/src/lib.rs

@@ -0,0 +1,522 @@
+//! Converts a text file into tokens
+#![warn(clippy::all)]
+#![feature(decl_macro)]
+use cl_structures::span::Loc;
+use cl_token::{TokenKind as Kind, *};
+use std::{
+    iter::Peekable,
+    str::{CharIndices, FromStr},
+};
+use unicode_ident::*;
+
+#[cfg(test)]
+mod tests;
+
+pub mod lexer_iter {
+    //! Iterator over a [`Lexer`], returning [`LResult<Token>`]s
+    use super::{
+        Lexer, Token,
+        error::{LResult, Reason},
+    };
+
+    /// Iterator over a [`Lexer`], returning [`LResult<Token>`]s
+    pub struct LexerIter<'t> {
+        lexer: Lexer<'t>,
+    }
+    impl Iterator for LexerIter<'_> {
+        type Item = LResult<Token>;
+        fn next(&mut self) -> Option<Self::Item> {
+            match self.lexer.scan() {
+                Ok(v) => Some(Ok(v)),
+                Err(e) => {
+                    if e.reason == Reason::EndOfFile {
+                        None
+                    } else {
+                        Some(Err(e))
+                    }
+                }
+            }
+        }
+    }
+    impl<'t> IntoIterator for Lexer<'t> {
+        type Item = LResult<Token>;
+        type IntoIter = LexerIter<'t>;
+        fn into_iter(self) -> Self::IntoIter {
+            LexerIter { lexer: self }
+        }
+    }
+}
+
+/// The Lexer iterates over the characters in a body of text, searching for [Tokens](Token).
+///
+/// # Examples
+/// ```rust
+/// # use cl_lexer::Lexer;
+/// # fn main() -> Result<(), Box<dyn std::error::Error>> {
+/// // Read in your code from somewhere
+/// let some_code = "
+/// fn main () {
+///     // TODO: code goes here!
+/// }
+/// ";
+/// // Create a lexer over your code
+/// let mut lexer = Lexer::new(some_code);
+/// // Scan for a single token
+/// let first_token = lexer.scan()?;
+/// println!("{first_token:?}");
+/// // Loop over all the rest of the tokens
+/// for token in lexer {
+/// #   let token: Result<_,()> = Ok(token?);
+///     match token {
+///         Ok(token) => println!("{token:?}"),
+///         Err(e) => eprintln!("{e:?}"),
+///     }
+/// }
+/// # Ok(()) }
+/// ```
+#[derive(Clone, Debug)]
+pub struct Lexer<'t> {
+    /// The source text
+    text: &'t str,
+    /// A peekable iterator over the source text
+    iter: Peekable<CharIndices<'t>>,
+    /// The end of the current token
+    head: usize,
+    /// The (line, col) end of the current token
+    head_loc: (u32, u32),
+    /// The start of the current token
+    tail: usize,
+    /// The (line, col) start of the current token
+    tail_loc: (u32, u32),
+}
+
+impl<'t> Lexer<'t> {
+    /// Creates a new [Lexer] over a [str]
+    pub fn new(text: &'t str) -> Self {
+        Self {
+            text,
+            iter: text.char_indices().peekable(),
+            head: 0,
+            head_loc: (1, 1),
+            tail: 0,
+            tail_loc: (1, 1),
+        }
+    }
+
+    /// Returns the current line
+    pub fn line(&self) -> u32 {
+        self.tail_loc.0
+    }
+
+    /// Returns the current column
+    pub fn col(&self) -> u32 {
+        self.tail_loc.1
+    }
+
+    /// Returns the current token's lexeme
+    fn lexeme(&mut self) -> &'t str {
+        &self.text[self.tail..self.head]
+    }
+
+    /// Peeks the next character without advancing the lexer
+    fn peek(&mut self) -> Option<char> {
+        self.iter.peek().map(|(_, c)| *c)
+    }
+
+    /// Advances the 'tail' (current position)
+    fn advance_tail(&mut self) {
+        let (idx, c) = self.iter.peek().copied().unwrap_or((self.text.len(), '\0'));
+        let (line, col) = &mut self.head_loc;
+        let diff = idx - self.head;
+
+        self.head = idx;
+        match c {
+            '\n' => {
+                *line += 1;
+                *col = 1;
+            }
+            _ => *col += diff as u32,
+        }
+    }
+
+    /// Takes the last-peeked character, or the next character if none peeked.
+    pub fn take(&mut self) -> Option<char> {
+        let (_, c) = self.iter.next()?;
+        self.advance_tail();
+        Some(c)
+    }
+
+    /// Takes the next char if it matches the `expected` char
+    pub fn next_if(&mut self, expected: char) -> Option<char> {
+        let (_, c) = self.iter.next_if(|&(_, c)| c == expected)?;
+        self.advance_tail();
+        Some(c)
+    }
+
+    /// Consumes the last-peeked character, advancing the tail
+    pub fn consume(&mut self) -> &mut Self {
+        self.iter.next();
+        self.advance_tail();
+        self
+    }
+
+    /// Produces an [Error] at the start of the current token
+    fn error(&self, reason: Reason) -> Error {
+        Error { reason, line: self.line(), col: self.col() }
+    }
+
+    /// Produces a token with the current [lexeme](Lexer::lexeme) as its data
+    fn produce(&mut self, kind: Kind) -> LResult<Token> {
+        let lexeme = self.lexeme().to_owned();
+        self.produce_with(kind, lexeme)
+    }
+
+    /// Produces a token with the provided `data`
+    fn produce_with(&mut self, kind: Kind, data: impl Into<TokenData>) -> LResult<Token> {
+        let loc = self.tail_loc;
+        self.tail_loc = self.head_loc;
+        self.tail = self.head;
+        Ok(Token::new(kind, data, loc.0, loc.1))
+    }
+
+    /// Produces a token with no `data`
+    fn produce_op(&mut self, kind: Kind) -> LResult<Token> {
+        self.produce_with(kind, ())
+    }
+
+    /// Consumes 0 or more whitespace
+    fn skip_whitespace(&mut self) -> &mut Self {
+        while self.peek().is_some_and(char::is_whitespace) {
+            let _ = self.consume();
+        }
+        self
+    }
+
+    /// Starts a new token
+    fn start_token(&mut self) -> &mut Self {
+        self.tail_loc = self.head_loc;
+        self.tail = self.head;
+        self
+    }
+
+    /// Scans through the text, searching for the next [Token]
+    pub fn scan(&mut self) -> LResult<Token> {
+        use TokenKind::*;
+        // !"#%&'()*+,-./:;<=>?@[\\]^`{|}~
+        let tok = match self
+            .skip_whitespace()
+            .start_token()
+            .peek()
+            .ok_or_else(|| self.error(Reason::EndOfFile))?
+        {
+            '!' => Bang,
+            '"' => return self.string(),
+            '#' => Hash,
+            '%' => Rem,
+            '&' => Amp,
+            '\'' => return self.character(),
+            '(' => LParen,
+            ')' => RParen,
+            '*' => Star,
+            '+' => Plus,
+            ',' => Comma,
+            '-' => Minus,
+            '.' => Dot,
+            '/' => Slash,
+            '0' => TokenKind::Literal,
+            '1'..='9' => return self.digits::<10>(),
+            ':' => Colon,
+            ';' => Semi,
+            '<' => Lt,
+            '=' => Eq,
+            '>' => Gt,
+            '?' => Question,
+            '@' => At,
+            '[' => LBrack,
+            '\\' => Backslash,
+            ']' => RBrack,
+            '^' => Xor,
+            '`' => Grave,
+            '{' => LCurly,
+            '|' => Bar,
+            '}' => RCurly,
+            '~' => Tilde,
+            '_' => return self.identifier(),
+            c if is_xid_start(c) => return self.identifier(),
+            e => {
+                let err = Err(self.error(Reason::UnexpectedChar(e)));
+                let _ = self.consume();
+                err?
+            }
+        };
+
+        // Handle digraphs
+        let tok = match (tok, self.consume().peek()) {
+            (Literal, Some('b')) => return self.consume().digits::<2>(),
+            (Literal, Some('d')) => return self.consume().digits::<10>(),
+            (Literal, Some('o')) => return self.consume().digits::<8>(),
+            (Literal, Some('x')) => return self.consume().digits::<16>(),
+            (Literal, Some('~')) => return self.consume().digits::<36>(),
+            (Literal, _) => return self.digits::<10>(),
+            (Amp, Some('&')) => AmpAmp,
+            (Amp, Some('=')) => AmpEq,
+            (Bang, Some('!')) => BangBang,
+            (Bang, Some('=')) => BangEq,
+            (Bar, Some('|')) => BarBar,
+            (Bar, Some('=')) => BarEq,
+            (Colon, Some(':')) => ColonColon,
+            (Dot, Some('.')) => DotDot,
+            (Eq, Some('=')) => EqEq,
+            (Eq, Some('>')) => FatArrow,
+            (Gt, Some('=')) => GtEq,
+            (Gt, Some('>')) => GtGt,
+            (Hash, Some('!')) => HashBang,
+            (Lt, Some('=')) => LtEq,
+            (Lt, Some('<')) => LtLt,
+            (Minus, Some('=')) => MinusEq,
+            (Minus, Some('>')) => Arrow,
+            (Plus, Some('=')) => PlusEq,
+            (Rem, Some('=')) => RemEq,
+            (Slash, Some('*')) => return self.block_comment()?.produce(Kind::Comment),
+            (Slash, Some('/')) => return self.line_comment(),
+            (Slash, Some('=')) => SlashEq,
+            (Star, Some('=')) => StarEq,
+            (Xor, Some('=')) => XorEq,
+            (Xor, Some('^')) => XorXor,
+            _ => return self.produce_op(tok),
+        };
+
+        // Handle trigraphs
+        let tok = match (tok, self.consume().peek()) {
+            (HashBang, Some('/')) => return self.line_comment(),
+            (DotDot, Some('=')) => DotDotEq,
+            (GtGt, Some('=')) => GtGtEq,
+            (LtLt, Some('=')) => LtLtEq,
+            _ => return self.produce_op(tok),
+        };
+
+        self.consume().produce_op(tok)
+    }
+}
+
+/// Comments
+impl Lexer<'_> {
+    /// Consumes until the next newline '\n', producing a [Comment](Kind::Comment)
+    fn line_comment(&mut self) -> LResult<Token> {
+        while self.consume().peek().is_some_and(|c| c != '\n') {}
+        self.produce(Kind::Comment)
+    }
+
+    /// Consumes nested block-comments. Does not produce by itself.
+    fn block_comment(&mut self) -> LResult<&mut Self> {
+        self.consume();
+        while let Some(c) = self.take() {
+            match (c, self.peek()) {
+                ('/', Some('*')) => self.block_comment()?,
+                ('*', Some('/')) => return Ok(self.consume()),
+                _ => continue,
+            };
+        }
+        Err(self.error(Reason::UnmatchedDelimiters('/')))
+    }
+}
+
+/// Identifiers
+impl Lexer<'_> {
+    /// Produces an [Identifier](Kind::Identifier) or keyword
+    fn identifier(&mut self) -> LResult<Token> {
+        while self.consume().peek().is_some_and(is_xid_continue) {}
+        if let Ok(keyword) = Kind::from_str(self.lexeme()) {
+            self.produce_with(keyword, ())
+        } else {
+            self.produce(Kind::Identifier)
+        }
+    }
+}
+
+/// Integers
+impl Lexer<'_> {
+    /// Produces a [Literal](Kind::Literal) with an integer or float value.
+    fn digits<const B: u32>(&mut self) -> LResult<Token> {
+        let mut value = 0;
+        while let Some(true) = self.peek().as_ref().map(char::is_ascii_alphanumeric) {
+            value = value * B as u128 + self.digit::<B>()? as u128;
+        }
+        // TODO: find a better way to handle floats in the tokenizer
+        match self.peek() {
+            Some('.') => {
+                // FIXME: hack: 0.. is not [0.0, '.']
+                if let Some('.') = self.clone().consume().take() {
+                    return self.produce_with(Kind::Literal, value);
+                }
+                let mut float = format!("{value}.");
+                self.consume();
+                while let Some(true) = self.peek().as_ref().map(char::is_ascii_digit) {
+                    float.push(self.iter.next().map(|(_, c)| c).unwrap_or_default());
+                }
+                let float = f64::from_str(&float).expect("must be parsable as float");
+                self.produce_with(Kind::Literal, float)
+            }
+            _ => self.produce_with(Kind::Literal, value),
+        }
+    }
+
+    /// Consumes a single digit of base [B](Lexer::digit)
+    fn digit<const B: u32>(&mut self) -> LResult<u32> {
+        let digit = self.take().ok_or_else(|| self.error(Reason::EndOfFile))?;
+        digit
+            .to_digit(B)
+            .ok_or_else(|| self.error(Reason::InvalidDigit(digit)))
+    }
+}
+
+/// Strings and characters
+impl Lexer<'_> {
+    /// Produces a [Literal](Kind::Literal) with a pre-escaped [String]
+    pub fn string(&mut self) -> Result<Token, Error> {
+        let mut lexeme = String::new();
+        let mut depth = 0;
+        self.consume();
+        loop {
+            lexeme.push(match self.take() {
+                None => Err(self.error(Reason::UnmatchedDelimiters('"')))?,
+                Some('\\') => self.unescape()?,
+                Some('"') if depth == 0 => break,
+                Some(c @ '{') => {
+                    depth += 1;
+                    c
+                }
+                Some(c @ '}') => {
+                    depth -= 1;
+                    c
+                }
+                Some(c) => c,
+            })
+        }
+        lexeme.shrink_to_fit();
+        self.produce_with(Kind::Literal, lexeme)
+    }
+
+    /// Produces a [Literal](Kind::Literal) with a pre-escaped [char]
+    fn character(&mut self) -> Result<Token, Error> {
+        let c = match self.consume().take() {
+            Some('\\') => self.unescape()?,
+            Some(c) => c,
+            None => '\0',
+        };
+        if self.take().is_some_and(|c| c == '\'') {
+            self.produce_with(Kind::Literal, c)
+        } else {
+            Err(self.error(Reason::UnmatchedDelimiters('\'')))
+        }
+    }
+
+    /// Unescapes a single character
+    #[rustfmt::skip]
+    fn unescape(&mut self) -> LResult<char> {
+        Ok(match self.take().ok_or_else(|| self.error(Reason::EndOfFile))? {
+            ' ' => '\u{a0}',
+            '0' => '\0',
+            'a' => '\x07',
+            'b' => '\x08',
+            'e' => '\x1b',
+            'f' => '\x0c',
+            'n' => '\n',
+            'r' => '\r',
+            't' => '\t',
+            'u' => self.unicode_escape()?,
+            'x' => self.hex_escape()?,
+            chr => chr,
+        })
+    }
+    /// Unescapes a single 2-digit hex escape
+    fn hex_escape(&mut self) -> LResult<char> {
+        let out = (self.digit::<16>()? << 4) + self.digit::<16>()?;
+        char::from_u32(out).ok_or_else(|| self.error(Reason::BadUnicode(out)))
+    }
+
+    /// Unescapes a single \u{} unicode escape
+    pub fn unicode_escape(&mut self) -> Result<char, Error> {
+        self.next_if('{')
+            .ok_or_else(|| self.error(Reason::InvalidEscape('u')))?;
+        let mut out = 0;
+        while let Some(c) = self.take() {
+            if c == '}' {
+                return char::from_u32(out).ok_or_else(|| self.error(Reason::BadUnicode(out)));
+            }
+            out = out * 16
+                + c.to_digit(16)
+                    .ok_or_else(|| self.error(Reason::InvalidDigit(c)))?;
+        }
+        Err(self.error(Reason::UnmatchedDelimiters('}')))
+    }
+}
+
+impl<'t> From<&Lexer<'t>> for Loc {
+    fn from(value: &Lexer<'t>) -> Self {
+        Loc(value.line(), value.col())
+    }
+}
+
+use error::{Error, LResult, Reason};
+pub mod error {
+    //! [Error] type for the [Lexer](super::Lexer)
+    use std::fmt::Display;
+
+    /// Result type with [Err] = [Error]
+    pub type LResult<T> = Result<T, Error>;
+    #[derive(Clone, Debug, PartialEq, Eq)]
+    pub struct Error {
+        pub reason: Reason,
+        pub line: u32,
+        pub col: u32,
+    }
+    /// The reason for the [Error]
+    #[derive(Clone, Copy, Debug, PartialEq, Eq)]
+    pub enum Reason {
+        /// Found an opening delimiter of type [char], but not the expected closing delimiter
+        UnmatchedDelimiters(char),
+        /// Found a character that doesn't belong to any [TokenKind](cl_token::TokenKind)
+        UnexpectedChar(char),
+        /// Found a character that's not valid in an escape sequence while looking for an escape
+        /// sequence
+        UnknownEscape(char),
+        /// Escape sequence contains invalid hexadecimal digit or unmatched braces
+        InvalidEscape(char),
+        /// Character is not a valid digit in the requested base
+        InvalidDigit(char),
+        /// Unicode escape does not map to a valid unicode code-point
+        BadUnicode(u32),
+        /// Reached end of input
+        EndOfFile,
+    }
+    impl Error {
+        /// Returns the [Reason] for this error
+        pub fn reason(&self) -> &Reason {
+            &self.reason
+        }
+        /// Returns the (line, col) where the error happened
+        pub fn location(&self) -> (u32, u32) {
+            (self.line, self.col)
+        }
+    }
+    impl std::error::Error for Error {}
+    impl Display for Error {
+        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+            write!(f, "{}:{}: {}", self.line, self.col, self.reason)
+        }
+    }
+    impl Display for Reason {
+        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+            match self {
+                Reason::UnmatchedDelimiters(c) => write! {f, "Unmatched `{c:?}` in input"},
+                Reason::UnexpectedChar(c) => write!(f, "Character `{c:?}` not expected"),
+                Reason::UnknownEscape(c) => write!(f, "`\\{c}` is not a known escape sequence"),
+                Reason::InvalidEscape(c) => write!(f, "Escape sequence `\\{c}`... is malformed"),
+                Reason::InvalidDigit(c) => write!(f, "`{c:?}` is not a valid digit"),
+                Reason::BadUnicode(c) => write!(f, "`\\u{{{c:x}}}` is not valid unicode"),
+                Reason::EndOfFile => write!(f, "Reached end of input"),
+            }
+        }
+    }
+}

compiler/cl-lexer/src/tests.rs

@@ -110,7 +110,7 @@ mod string {
 }
 mod punct {
     macro op($op:ident) {
-        TokenKind::Punct(Punct::$op)
+        TokenKind::$op
     }
 
     use super::*;

compiler/cl-parser/src/error.rs

@@ -1,5 +1,6 @@
 use super::*;
 
+use cl_ast::{Expr, Sym};
 use cl_lexer::error::{Error as LexError, Reason};
 use std::fmt::Display;
 pub type PResult<T> = Result<T, Error>;
@@ -7,6 +8,7 @@ pub type PResult<T> = Result<T, Error>;
 /// Contains information about [Parser] errors
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct Error {
+    pub in_file: Sym,
     pub reason: ErrorKind,
     pub while_parsing: Parsing,
     pub loc: Loc,
@@ -22,14 +24,16 @@ pub enum ErrorKind {
     UnmatchedCurlyBraces,
     UnmatchedSquareBrackets,
     Unexpected(TokenKind),
-    Expected {
+    ExpectedToken {
         want: TokenKind,
         got: TokenKind,
     },
-    /// No rules matched
-    Nothing,
+    ExpectedParsing {
+        want: Parsing,
+    },
+    InvalidPattern(Box<Expr>),
     /// Indicates unfinished code
-    Todo,
+    Todo(&'static str),
 }
 impl From<LexError> for ErrorKind {
     fn from(value: LexError) -> Self {
@@ -43,15 +47,20 @@ impl From<LexError> for ErrorKind {
 /// Compactly represents the stage of parsing an [Error] originated in
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub enum Parsing {
+    Mutability,
+    Visibility,
+    Identifier,
+    Literal,
+
     File,
 
     Attrs,
     Meta,
+    MetaKind,
 
     Item,
-    Visibility,
-    Mutability,
     ItemKind,
+    Generics,
     Alias,
     Const,
     Static,
@@ -67,38 +76,47 @@ pub enum Parsing {
     Variant,
     VariantKind,
     Impl,
+    ImplKind,
+    Use,
+    UseTree,
 
     Ty,
     TyKind,
+    TySlice,
+    TyArray,
     TyTuple,
     TyRef,
     TyFn,
 
+    Path,
+    PathPart,
+
     Stmt,
     StmtKind,
     Let,
 
     Expr,
     ExprKind,
+    Closure,
     Assign,
     AssignKind,
     Binary,
     BinaryKind,
     Unary,
     UnaryKind,
+    Cast,
     Index,
+    Structor,
+    Fielder,
     Call,
     Member,
-    PathExpr,
-    PathPart,
-    Identifier,
-    Literal,
     Array,
     ArrayRep,
     AddrOf,
     Block,
     Group,
     Tuple,
+    Loop,
     While,
     If,
     For,
@@ -106,17 +124,26 @@ pub enum Parsing {
     Break,
     Return,
     Continue,
+
+    Pattern,
+    Match,
+    MatchArm,
 }
 
 impl Display for Error {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        let Self { reason, while_parsing, loc } = self;
+        let Self { in_file, reason, while_parsing, loc } = self;
         match reason {
             // TODO entries are debug-printed
-            ErrorKind::Todo => write!(f, "{loc} {reason} {while_parsing:?}"),
+            ErrorKind::Todo(_) => write!(f, "{in_file}:{loc} {reason} {while_parsing:?}"),
             // lexical errors print their own higher-resolution loc info
             ErrorKind::Lexical(e) => write!(f, "{e} (while parsing {while_parsing})"),
-            _ => write!(f, "{loc} {reason} while parsing {while_parsing}"),
+            _ => {
+                if !in_file.is_empty() {
+                    write!(f, "{in_file}:")?
+                }
+                write!(f, "{loc}: {reason} while parsing {while_parsing}")
+            }
         }
     }
 }
@@ -129,26 +156,29 @@ impl Display for ErrorKind {
             ErrorKind::UnmatchedCurlyBraces => write!(f, "Unmatched curly braces"),
             ErrorKind::UnmatchedSquareBrackets => write!(f, "Unmatched square brackets"),
             ErrorKind::Unexpected(t) => write!(f, "Encountered unexpected token `{t}`"),
-            ErrorKind::Expected { want: e, got: g } => {
-                write!(f, "Expected `{e}`, got `{g}`")
-            }
-            ErrorKind::Nothing => write!(f, "Nothing found"),
-            ErrorKind::Todo => write!(f, "TODO:"),
+            ErrorKind::ExpectedToken { want: e, got: g } => write!(f, "Expected `{e}`, got `{g}`"),
+            ErrorKind::ExpectedParsing { want } => write!(f, "Expected {want}"),
+            ErrorKind::InvalidPattern(got) => write!(f, "Got invalid `{got}`"),
+            ErrorKind::Todo(unfinished) => write!(f, "TODO: {unfinished}"),
         }
     }
 }
 impl Display for Parsing {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
+            Parsing::Visibility => "a visibility qualifier",
+            Parsing::Mutability => "a mutability qualifier",
+            Parsing::Identifier => "an identifier",
+            Parsing::Literal => "a literal",
+
             Parsing::File => "a file",
 
             Parsing::Attrs => "an attribute-set",
             Parsing::Meta => "an attribute",
-
+            Parsing::MetaKind => "an attribute's arguments",
             Parsing::Item => "an item",
-            Parsing::Visibility => "a visibility qualifier",
-            Parsing::Mutability => "a mutability qualifier",
             Parsing::ItemKind => "an item",
+            Parsing::Generics => "a list of type arguments",
             Parsing::Alias => "a type alias",
             Parsing::Const => "a const item",
             Parsing::Static => "a static variable",
@@ -164,38 +194,47 @@ impl Display for Parsing {
             Parsing::Variant => "an enum variant",
             Parsing::VariantKind => "an enum variant",
             Parsing::Impl => "an impl block",
+            Parsing::ImplKind => "the target of an impl block",
+            Parsing::Use => "a use item",
+            Parsing::UseTree => "a use-tree",
 
             Parsing::Ty => "a type",
             Parsing::TyKind => "a type",
+            Parsing::TySlice => "a slice type",
+            Parsing::TyArray => "an array type",
             Parsing::TyTuple => "a tuple of types",
             Parsing::TyRef => "a reference type",
             Parsing::TyFn => "a function pointer type",
 
+            Parsing::Path => "a path",
+            Parsing::PathPart => "a path component",
+
             Parsing::Stmt => "a statement",
             Parsing::StmtKind => "a statement",
             Parsing::Let => "a local variable declaration",
 
             Parsing::Expr => "an expression",
             Parsing::ExprKind => "an expression",
+            Parsing::Closure => "an anonymous function",
             Parsing::Assign => "an assignment",
             Parsing::AssignKind => "an assignment operator",
             Parsing::Binary => "a binary expression",
             Parsing::BinaryKind => "a binary operator",
             Parsing::Unary => "a unary expression",
             Parsing::UnaryKind => "a unary operator",
+            Parsing::Cast => "an `as`-casting expression",
             Parsing::Index => "an indexing expression",
+            Parsing::Structor => "a struct constructor expression",
+            Parsing::Fielder => "a struct field expression",
             Parsing::Call => "a call expression",
             Parsing::Member => "a member access expression",
-            Parsing::PathExpr => "a path",
-            Parsing::PathPart => "a path component",
-            Parsing::Identifier => "an identifier",
-            Parsing::Literal => "a literal",
             Parsing::Array => "an array",
             Parsing::ArrayRep => "an array of form [k;N]",
             Parsing::AddrOf => "a borrow op",
             Parsing::Block => "a block",
             Parsing::Group => "a grouped expression",
             Parsing::Tuple => "a tuple",
+            Parsing::Loop => "an unconditional loop expression",
             Parsing::While => "a while expression",
             Parsing::If => "an if expression",
             Parsing::For => "a for expression",
@@ -203,6 +242,10 @@ impl Display for Parsing {
             Parsing::Break => "a break expression",
             Parsing::Return => "a return expression",
             Parsing::Continue => "a continue expression",
+
+            Parsing::Pattern => "a pattern",
+            Parsing::Match => "a match expression",
+            Parsing::MatchArm => "a match arm",
         }
         .fmt(f)
     }

compiler/cl-parser/src/inliner.rs

@@ -0,0 +1,118 @@
+//! The [ModuleInliner] reads files described in the module structure of the
+
+use crate::Parser;
+use cl_ast::{ast_visitor::Fold, *};
+use cl_lexer::Lexer;
+use std::path::{Path, PathBuf};
+
+pub type IoErrs = Vec<(PathBuf, std::io::Error)>;
+pub type ParseErrs = Vec<(PathBuf, crate::error::Error)>;
+
+pub struct ModuleInliner {
+    path: PathBuf,
+    io_errs: IoErrs,
+    parse_errs: ParseErrs,
+}
+
+impl ModuleInliner {
+    /// Creates a new [ModuleInliner]
+    pub fn new(root: impl AsRef<Path>) -> Self {
+        Self {
+            path: root.as_ref().to_path_buf(),
+            io_errs: Default::default(),
+            parse_errs: Default::default(),
+        }
+    }
+
+    /// Returns true when the [ModuleInliner] has errors to report
+    pub fn has_errors(&self) -> bool {
+        !(self.io_errs.is_empty() && self.parse_errs.is_empty())
+    }
+
+    /// Returns the [IO Errors](IoErrs) and [parse Errors](ParseErrs)
+    pub fn into_errs(self) -> Option<(IoErrs, ParseErrs)> {
+        self.has_errors().then_some((self.io_errs, self.parse_errs))
+    }
+
+    /// Traverses a [File], attempting to inline all submodules.
+    ///
+    /// This is a simple wrapper around [ModuleInliner::fold_file()] and
+    /// [ModuleInliner::into_errs()]
+    pub fn inline(mut self, file: File) -> Result<File, (File, IoErrs, ParseErrs)> {
+        let file = self.fold_file(file);
+
+        match self.into_errs() {
+            Some((io, parse)) => Err((file, io, parse)),
+            None => Ok(file),
+        }
+    }
+
+    /// Records an [I/O error](std::io::Error) for later
+    fn handle_io_error(&mut self, error: std::io::Error) -> Option<File> {
+        self.io_errs.push((self.path.clone(), error));
+        None
+    }
+
+    /// Records a [parse error](crate::error::Error) for later
+    fn handle_parse_error(&mut self, error: crate::error::Error) -> Option<File> {
+        self.parse_errs.push((self.path.clone(), error));
+        None
+    }
+}
+
+impl Fold for ModuleInliner {
+    /// Traverses down the module tree, entering ever nested directories
+    fn fold_module(&mut self, m: Module) -> Module {
+        let Module { name, file } = m;
+        self.path.push(&*name); // cd ./name
+
+        let file = self.fold_module_kind(file);
+
+        self.path.pop(); // cd ..
+        Module { name, file }
+    }
+}
+
+impl ModuleInliner {
+    /// Attempts to read and parse a file for every module in the tree
+    fn fold_module_kind(&mut self, m: Option<File>) -> Option<File> {
+        use std::borrow::Cow;
+        if let Some(f) = m {
+            return Some(self.fold_file(f));
+        }
+
+        // cd path/mod.cl
+        self.path.set_extension("cl");
+        let mut used_path: Cow<Path> = Cow::Borrowed(&self.path);
+
+        let file = match std::fs::read_to_string(&self.path) {
+            Err(error) => {
+                let Some(basename) = self.path.file_name() else {
+                    return self.handle_io_error(error);
+                };
+                used_path = Cow::Owned(
+                    self.path
+                        .parent()
+                        .and_then(Path::parent)
+                        .map(|path| path.join(basename))
+                        .unwrap_or_default(),
+                );
+
+                match std::fs::read_to_string(&used_path) {
+                    Err(error) => return self.handle_io_error(error),
+                    Ok(file) => file,
+                }
+            }
+            Ok(file) => file,
+        };
+
+        match Parser::new(used_path.display().to_string(), Lexer::new(&file)).parse() {
+            Err(e) => self.handle_parse_error(e),
+            Ok(file) => {
+                self.path.set_extension("");
+                // The newly loaded module may need further inlining
+                Some(self.fold_file(file))
+            }
+        }
+    }
+}

compiler/cl-parser/src/lib.rs

@@ -14,3 +14,5 @@ use cl_token::*;
 pub mod error;
 
 pub mod parser;
+
+pub mod inliner;

compiler/cl-parser/src/parser/prec.rs

@@ -0,0 +1,425 @@
+//! Parses an [ExprKind] using a modified pratt parser
+//!
+//! See also: [Expr::parse], [ExprKind::parse]
+//!
+//! Implementer's note: [ExprKind::parse] is the public API for parsing [ExprKind]s.
+//! Do not call it from within this function.
+
+use super::{Parse, *};
+
+/// Parses an [ExprKind]
+pub fn expr(p: &mut Parser, power: u8) -> PResult<Expr> {
+    let parsing = Parsing::ExprKind;
+    let start = p.loc();
+    // Prefix expressions
+    let mut head = Expr {
+        kind: match p.peek_kind(Parsing::Unary)? {
+            literal_like!() => Literal::parse(p)?.into(),
+            path_like!() => exprkind_pathlike(p)?,
+            TokenKind::Amp | TokenKind::AmpAmp => AddrOf::parse(p)?.into(),
+            TokenKind::Bar | TokenKind::BarBar => Closure::parse(p)?.into(),
+            TokenKind::Grave => Quote::parse(p)?.into(),
+            TokenKind::LCurly => Block::parse(p)?.into(),
+            TokenKind::LBrack => exprkind_arraylike(p)?,
+            TokenKind::LParen => exprkind_tuplelike(p)?,
+            TokenKind::Let => Let::parse(p)?.into(),
+            TokenKind::Match => Match::parse(p)?.into(),
+            TokenKind::While => ExprKind::While(While::parse(p)?),
+            TokenKind::If => ExprKind::If(If::parse(p)?),
+            TokenKind::For => ExprKind::For(For::parse(p)?),
+            TokenKind::Break => ExprKind::Break(Break::parse(p)?),
+            TokenKind::Return => ExprKind::Return(Return::parse(p)?),
+            TokenKind::Continue => {
+                p.consume_peeked();
+                ExprKind::Continue
+            }
+
+            op => {
+                let (kind, prec) =
+                    from_prefix(op).ok_or_else(|| p.error(Unexpected(op), parsing))?;
+                let ((), after) = prec.prefix().expect("should have a precedence");
+                p.consume_peeked();
+                Unary { kind, tail: expr(p, after)?.into() }.into()
+            }
+        },
+        span: Span(start, p.loc()),
+    };
+
+    fn from_postfix(op: TokenKind) -> Option<Precedence> {
+        Some(match op {
+            TokenKind::LBrack => Precedence::Index,
+            TokenKind::LParen => Precedence::Call,
+            TokenKind::LCurly => Precedence::Structor,
+            TokenKind::Dot => Precedence::Member,
+            TokenKind::As => Precedence::Cast,
+            _ => None?,
+        })
+    }
+
+    while let Ok(op) = p.peek_kind(parsing) {
+        // Postfix expressions
+        if let Some((before, ())) = from_postfix(op).and_then(Precedence::postfix) {
+            if before < power {
+                break;
+            }
+
+            head = Expr {
+                kind: match op {
+                    TokenKind::LBrack => {
+                        p.consume_peeked();
+                        let indices =
+                            sep(Expr::parse, TokenKind::Comma, TokenKind::RBrack, parsing)(p)?;
+                        p.match_type(TokenKind::RBrack, parsing)?;
+                        ExprKind::Index(Index { head: head.into(), indices })
+                    }
+                    TokenKind::LParen => {
+                        p.consume_peeked();
+                        let exprs =
+                            sep(Expr::parse, TokenKind::Comma, TokenKind::RParen, parsing)(p)?;
+                        p.match_type(TokenKind::RParen, parsing)?;
+                        Binary {
+                            kind: BinaryKind::Call,
+                            parts: (
+                                head,
+                                Expr { kind: Tuple { exprs }.into(), span: Span(start, p.loc()) },
+                            )
+                                .into(),
+                        }
+                        .into()
+                    }
+                    TokenKind::LCurly => match head.kind {
+                        ExprKind::Path(path) => ExprKind::Structor(structor_body(p, path)?),
+                        _ => break,
+                    },
+                    TokenKind::Dot => {
+                        p.consume_peeked();
+                        let kind = MemberKind::parse(p)?;
+                        Member { head: Box::new(head), kind }.into()
+                    }
+                    TokenKind::As => {
+                        p.consume_peeked();
+                        let ty = Ty::parse(p)?;
+                        Cast { head: head.into(), ty }.into()
+                    }
+                    _ => Err(p.error(Unexpected(op), parsing))?,
+                },
+                span: Span(start, p.loc()),
+            };
+            continue;
+        }
+        // infix expressions
+        if let Some((kind, prec)) = from_infix(op) {
+            let (before, after) = prec.infix().expect("should have a precedence");
+            if before < power {
+                break;
+            }
+            p.consume_peeked();
+
+            let tail = expr(p, after)?;
+            head = Expr {
+                kind: Binary { kind, parts: (head, tail).into() }.into(),
+                span: Span(start, p.loc()),
+            };
+            continue;
+        }
+
+        if let Some((kind, prec)) = from_modify(op) {
+            let (before, after) = prec.infix().expect("should have a precedence");
+            if before < power {
+                break;
+            }
+            p.consume_peeked();
+
+            let tail = expr(p, after)?;
+            head = Expr {
+                kind: Modify { kind, parts: (head, tail).into() }.into(),
+                span: Span(start, p.loc()),
+            };
+            continue;
+        }
+
+        if let TokenKind::Eq = op {
+            let (before, after) = Precedence::Assign
+                .infix()
+                .expect("should have a precedence");
+            if before < power {
+                break;
+            }
+            p.consume_peeked();
+
+            let tail = expr(p, after)?;
+            head = Expr {
+                kind: Assign { parts: (head, tail).into() }.into(),
+                span: Span(start, p.loc()),
+            };
+
+            continue;
+        }
+
+        if let TokenKind::As = op {
+            let before = Precedence::Cast.level();
+            if before < power {
+                break;
+            }
+            p.consume_peeked();
+
+            let ty = Ty::parse(p)?;
+            head = Expr { kind: Cast { head: head.into(), ty }.into(), span: Span(start, p.loc()) };
+
+            continue;
+        }
+
+        break;
+    }
+
+    Ok(head)
+}
+
+/// [Array] = '[' ([Expr] ',')* [Expr]? ']'
+///
+/// Array and ArrayRef are ambiguous until the second token,
+/// so they can't be independent subexpressions
+fn exprkind_arraylike(p: &mut Parser) -> PResult<ExprKind> {
+    const P: Parsing = Parsing::Array;
+    const START: TokenKind = TokenKind::LBrack;
+    const END: TokenKind = TokenKind::RBrack;
+
+    p.match_type(START, P)?;
+    let out = match p.peek_kind(P)? {
+        END => Array { values: vec![] }.into(),
+        _ => exprkind_array_rep(p)?,
+    };
+    p.match_type(END, P)?;
+    Ok(out)
+}
+
+/// [ArrayRep] = `[` [Expr] `;` [Expr] `]`
+fn exprkind_array_rep(p: &mut Parser) -> PResult<ExprKind> {
+    const P: Parsing = Parsing::Array;
+    const END: TokenKind = TokenKind::RBrack;
+
+    let first = Expr::parse(p)?;
+    Ok(match p.peek_kind(P)? {
+        TokenKind::Semi => ArrayRep {
+            value: first.into(),
+            repeat: {
+                p.consume_peeked();
+                p.parse()?
+            },
+        }
+        .into(),
+        TokenKind::RBrack => Array { values: vec![first] }.into(),
+        TokenKind::Comma => Array {
+            values: {
+                p.consume_peeked();
+                let mut out = vec![first];
+                out.extend(sep(Expr::parse, TokenKind::Comma, END, P)(p)?);
+                out
+            },
+        }
+        .into(),
+        ty => Err(p.error(Unexpected(ty), P))?,
+    })
+}
+
+/// [Group] = `(`([Empty](ExprKind::Empty)|[Expr]|[Tuple])`)`
+///
+/// [ExprKind::Empty] and [Group] are special cases of [Tuple]
+fn exprkind_tuplelike(p: &mut Parser) -> PResult<ExprKind> {
+    p.match_type(TokenKind::LParen, Parsing::Group)?;
+    let out = match p.peek_kind(Parsing::Group)? {
+        TokenKind::RParen => Ok(ExprKind::Empty),
+        _ => exprkind_group(p),
+    };
+    p.match_type(TokenKind::RParen, Parsing::Group)?;
+    out
+}
+
+/// [Group] = `(`([Empty](ExprKind::Empty)|[Expr]|[Tuple])`)`
+fn exprkind_group(p: &mut Parser) -> PResult<ExprKind> {
+    let first = Expr::parse(p)?;
+    match p.peek_kind(Parsing::Group)? {
+        TokenKind::Comma => {
+            let mut exprs = vec![first];
+            p.consume_peeked();
+            while TokenKind::RParen != p.peek_kind(Parsing::Tuple)? {
+                exprs.push(Expr::parse(p)?);
+                match p.peek_kind(Parsing::Tuple)? {
+                    TokenKind::Comma => p.consume_peeked(),
+                    _ => break,
+                };
+            }
+            Ok(Tuple { exprs }.into())
+        }
+        _ => Ok(Group { expr: first.into() }.into()),
+    }
+}
+
+/// Parses an expression beginning with a [Path] (i.e. [Path] or [Structor])
+fn exprkind_pathlike(p: &mut Parser) -> PResult<ExprKind> {
+    Path::parse(p).map(Into::into)
+}
+
+/// [Structor]Body = `{` ([Fielder] `,`)* [Fielder]? `}`
+fn structor_body(p: &mut Parser, to: Path) -> PResult<Structor> {
+    let init = delim(
+        sep(
+            Fielder::parse,
+            TokenKind::Comma,
+            CURLIES.1,
+            Parsing::Structor,
+        ),
+        CURLIES,
+        Parsing::Structor,
+    )(p)?;
+
+    Ok(Structor { to, init })
+}
+
+/// Precedence provides a total ordering among operators
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum Precedence {
+    Assign,
+    Structor,  // A structor is never a valid conditional
+    Condition, // Anything that syntactically needs a block following it
+    Logic,
+    Compare,
+    Range,
+    Bitwise,
+    Shift,
+    Factor,
+    Term,
+    Unary,
+    Index,
+    Cast,
+    Member, // left-associative
+    Call,
+    Deref,
+}
+
+impl Precedence {
+    #[inline]
+    pub const fn level(self) -> u8 {
+        (self as u8) << 1
+    }
+
+    pub fn prefix(self) -> Option<((), u8)> {
+        match self {
+            Self::Assign => Some(((), self.level())),
+            Self::Unary => Some(((), self.level())),
+            Self::Deref => Some(((), self.level())),
+            _ => None,
+        }
+    }
+
+    pub fn infix(self) -> Option<(u8, u8)> {
+        let level = self.level();
+        match self {
+            Self::Unary => None,
+            Self::Assign => Some((level + 1, level)),
+            _ => Some((level, level + 1)),
+        }
+    }
+
+    pub fn postfix(self) -> Option<(u8, ())> {
+        match self {
+            Self::Structor | Self::Index | Self::Call | Self::Member | Self::Cast => {
+                Some((self.level(), ()))
+            }
+            _ => None,
+        }
+    }
+}
+
+impl From<ModifyKind> for Precedence {
+    fn from(_value: ModifyKind) -> Self {
+        Precedence::Assign
+    }
+}
+
+impl From<BinaryKind> for Precedence {
+    fn from(value: BinaryKind) -> Self {
+        use BinaryKind as Op;
+        match value {
+            Op::Call => Precedence::Call,
+            Op::Mul | Op::Div | Op::Rem => Precedence::Term,
+            Op::Add | Op::Sub => Precedence::Factor,
+            Op::Shl | Op::Shr => Precedence::Shift,
+            Op::BitAnd | Op::BitOr | Op::BitXor => Precedence::Bitwise,
+            Op::LogAnd | Op::LogOr | Op::LogXor => Precedence::Logic,
+            Op::RangeExc | Op::RangeInc => Precedence::Range,
+            Op::Lt | Op::LtEq | Op::Equal | Op::NotEq | Op::GtEq | Op::Gt => Precedence::Compare,
+        }
+    }
+}
+
+impl From<UnaryKind> for Precedence {
+    fn from(value: UnaryKind) -> Self {
+        use UnaryKind as Op;
+        match value {
+            Op::Loop => Precedence::Assign,
+            Op::Deref => Precedence::Deref,
+            _ => Precedence::Unary,
+        }
+    }
+}
+
+/// Creates helper functions for turning TokenKinds into AST operators
+macro operator($($name:ident ($takes:ident => $returns:ident) {$($t:ident => $p:ident),*$(,)?};)*) {$(
+    pub fn $name (value: $takes) -> Option<($returns, Precedence)> {
+        match value {
+            $($takes::$t => Some(($returns::$p, Precedence::from($returns::$p))),)*
+            _ => None?,
+        }
+    })*
+}
+
+operator! {
+    from_prefix (TokenKind => UnaryKind) {
+        Loop => Loop,
+        Star => Deref,
+        Minus => Neg,
+        Bang => Not,
+        DotDot => RangeExc,
+        DotDotEq => RangeInc,
+        At => At,
+        Tilde => Tilde,
+    };
+
+    from_modify(TokenKind => ModifyKind) {
+        AmpEq => And,
+        BarEq => Or,
+        XorEq => Xor,
+        LtLtEq => Shl,
+        GtGtEq => Shr,
+        PlusEq => Add,
+        MinusEq => Sub,
+        StarEq => Mul,
+        SlashEq => Div,
+        RemEq => Rem,
+    };
+
+    from_infix (TokenKind => BinaryKind) {
+        Lt => Lt,
+        LtEq => LtEq,
+        EqEq => Equal,
+        BangEq => NotEq,
+        GtEq => GtEq,
+        Gt => Gt,
+        DotDot => RangeExc,
+        DotDotEq => RangeInc,
+        AmpAmp => LogAnd,
+        BarBar => LogOr,
+        XorXor => LogXor,
+        Amp => BitAnd,
+        Bar => BitOr,
+        Xor => BitXor,
+        LtLt => Shl,
+        GtGt => Shr,
+        Plus => Add,
+        Minus => Sub,
+        Star => Mul,
+        Slash => Div,
+        Rem => Rem,
+    };
+}

compiler/cl-repl/Cargo.toml

@@ -14,10 +14,9 @@ cl-ast = { path = "../cl-ast" }
 cl-lexer = { path = "../cl-lexer" }
 cl-token = { path = "../cl-token" }
 cl-parser = { path = "../cl-parser" }
-cl-interpret = { path = "../cl-interpret" }
-crossterm = "0.27.0"
-argh = "0.1.12"
-
-[dev-dependencies]
-cl-structures = { path = "../cl-structures" }
 cl-typeck = { path = "../cl-typeck" }
+cl-interpret = { path = "../cl-interpret" }
+cl-structures = { path = "../cl-structures" }
+cl-arena = { version = "0", registry = "soft-fish" }
+repline = { version = "*", registry = "soft-fish" }
+argwerk = "0.20.4"

compiler/cl-repl/examples/identify_tokens.rs

@@ -4,7 +4,7 @@ use cl_lexer::Lexer;
 use cl_token::Token;
 use std::{
     error::Error,
-    io::{stdin, IsTerminal, Read},
+    io::{IsTerminal, Read, stdin},
     path::{Path, PathBuf},
 };
 

compiler/cl-repl/examples/to_c.rs

@@ -0,0 +1,951 @@
+//! Pretty prints a conlang AST in yaml
+
+use cl_ast::{File, Stmt};
+use cl_lexer::Lexer;
+use cl_parser::Parser;
+use repline::{Repline, error::Error as RlError};
+use std::error::Error;
+
+fn main() -> Result<(), Box<dyn Error>> {
+    if let Some(path) = std::env::args().nth(1) {
+        let f = std::fs::read_to_string(&path).expect("Path must be valid.");
+        let mut parser = Parser::new(path, Lexer::new(&f));
+        let code: File = match parser.parse() {
+            Ok(f) => f,
+            Err(e) => {
+                eprintln!("{e}");
+                return Ok(());
+            }
+        };
+        CLangifier::new().p(&code);
+        println!();
+        return Ok(());
+    }
+    let mut rl = Repline::new("\x1b[33m", "cl>", "? >");
+    loop {
+        let mut line = match rl.read() {
+            Err(RlError::CtrlC(_)) => break,
+            Err(RlError::CtrlD(line)) => {
+                rl.deny();
+                line
+            }
+            Ok(line) => line,
+            Err(e) => Err(e)?,
+        };
+        if !line.ends_with(';') {
+            line.push(';');
+        }
+
+        let mut parser = Parser::new("stdin", Lexer::new(&line));
+        let code = match parser.parse::<Stmt>() {
+            Ok(code) => {
+                rl.accept();
+                code
+            }
+            Err(e) => {
+                print!("\x1b[40G\x1bJ\x1b[91m{e}\x1b[0m");
+                continue;
+            }
+        };
+        print!("\x1b[G\x1b[J");
+        CLangifier::new().p(&code);
+        println!();
+    }
+    Ok(())
+}
+
+pub use clangifier::CLangifier;
+pub mod clangifier {
+    use crate::clangify::CLangify;
+    use std::{
+        fmt::Display,
+        io::Write,
+        ops::{Add, Deref, DerefMut},
+    };
+    #[derive(Debug, Default)]
+    pub struct CLangifier {
+        depth: usize,
+    }
+
+    impl CLangifier {
+        pub fn new() -> Self {
+            Self::default()
+        }
+
+        pub fn indent(&mut self) -> Section<'_> {
+            Section::new(self)
+        }
+
+        /// Prints a [Yamlify] value
+        #[inline]
+        pub fn p<T: CLangify + ?Sized>(&mut self, yaml: &T) -> &mut Self {
+            yaml.print(self);
+            self
+        }
+
+        fn increase(&mut self) {
+            self.depth += 1;
+        }
+
+        fn decrease(&mut self) {
+            self.depth -= 1;
+        }
+
+        fn print_indentation(&self, writer: &mut impl Write) {
+            for _ in 0..self.depth {
+                let _ = write!(writer, "    ");
+            }
+        }
+
+        pub fn endl(&mut self) -> &mut Self {
+            self.p("\n")
+                .print_indentation(&mut std::io::stdout().lock());
+            self
+        }
+
+        /// Prints a section header and increases indentation
+        pub fn nest(&mut self, name: impl Display) -> Section<'_> {
+            print!("{name}");
+            self.indent()
+        }
+    }
+
+    impl<C: CLangify + ?Sized> Add<&C> for &mut CLangifier {
+        type Output = Self;
+
+        fn add(self, rhs: &C) -> Self::Output {
+            self.p(rhs)
+        }
+    }
+
+    /// Tracks the start and end of an indented block (a "section")
+    pub struct Section<'y> {
+        yamler: &'y mut CLangifier,
+    }
+
+    impl<'y> Section<'y> {
+        pub fn new(yamler: &'y mut CLangifier) -> Self {
+            yamler.increase();
+            Self { yamler }
+        }
+    }
+
+    impl Deref for Section<'_> {
+        type Target = CLangifier;
+        fn deref(&self) -> &Self::Target {
+            self.yamler
+        }
+    }
+    impl DerefMut for Section<'_> {
+        fn deref_mut(&mut self) -> &mut Self::Target {
+            self.yamler
+        }
+    }
+
+    impl Drop for Section<'_> {
+        fn drop(&mut self) {
+            let Self { yamler } = self;
+            yamler.decrease();
+        }
+    }
+}
+
+pub mod clangify {
+    use core::panic;
+    use std::iter;
+
+    use super::clangifier::CLangifier;
+    use cl_ast::*;
+
+    pub trait CLangify {
+        fn print(&self, y: &mut CLangifier);
+    }
+
+    impl CLangify for File {
+        fn print(&self, mut y: &mut CLangifier) {
+            let File { name, items } = self;
+            // TODO: turn name into include guard
+            y = (y + "// Generated from " + name).endl();
+            for (idx, item) in items.iter().enumerate() {
+                if idx > 0 {
+                    y.endl().endl();
+                }
+                y.p(item);
+            }
+            y.endl();
+        }
+    }
+    impl CLangify for Visibility {
+        fn print(&self, _y: &mut CLangifier) {}
+    }
+    impl CLangify for Mutability {
+        fn print(&self, y: &mut CLangifier) {
+            if let Mutability::Not = self {
+                y.p("const ");
+            }
+        }
+    }
+
+    impl CLangify for Attrs {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { meta } = self;
+            y.nest("Attrs").p(meta);
+            todo!("Attributes");
+        }
+    }
+    impl CLangify for Meta {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { name, kind } = self;
+            y.nest("Meta").p(name).p(kind);
+            todo!("Attributes");
+        }
+    }
+    impl CLangify for MetaKind {
+        fn print(&self, y: &mut CLangifier) {
+            match self {
+                MetaKind::Plain => y,
+                MetaKind::Equals(value) => y.p(value),
+                MetaKind::Func(args) => y.p(args),
+            };
+            todo!("Attributes");
+        }
+    }
+
+    impl CLangify for Item {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { span: _, attrs: _, vis, kind } = self;
+            y.p(vis).p(kind);
+        }
+    }
+    impl CLangify for ItemKind {
+        fn print(&self, y: &mut CLangifier) {
+            match self {
+                ItemKind::Alias(f) => y.p(f),
+                ItemKind::Const(f) => y.p(f),
+                ItemKind::Static(f) => y.p(f),
+                ItemKind::Module(f) => y.p(f),
+                ItemKind::Function(f) => y.p(f),
+                ItemKind::Struct(f) => y.p(f),
+                ItemKind::Enum(f) => y.p(f),
+                ItemKind::Impl(f) => y.p(f),
+                ItemKind::Use(f) => y.p(f),
+            };
+        }
+    }
+    impl CLangify for Generics {
+        fn print(&self, _y: &mut CLangifier) {
+            let Self { vars } = self;
+            if !vars.is_empty() {
+                panic!("C doesn't have generics, dumbass.")
+            }
+        }
+    }
+    impl CLangify for Alias {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { name, from } = self;
+            y.p("typedef ").p(from).p(" ");
+            y.p(name).p("; ");
+        }
+    }
+    impl CLangify for Const {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { name, ty, init } = self;
+            y.p("const ").p(ty).p(" ");
+            y.p(name).p(" = ").p(init);
+        }
+    }
+    impl CLangify for Static {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { mutable, name, ty, init } = self;
+            y.p(mutable).p(ty).p(" ");
+            y.p(name).p(" = ").p(init);
+        }
+    }
+    impl CLangify for Module {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { name, file } = self;
+            y.nest("// mod ").p(name).p(" {").endl();
+            y.p(file);
+            y.endl().p("// } mod ").p(name);
+        }
+    }
+    impl CLangify for Function {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { name, gens: _, sign, bind, body } = self;
+            let TyFn { args, rety } = sign;
+            let types = match &args.kind {
+                TyKind::Tuple(TyTuple { types }) => types.as_slice(),
+                _ => panic!("Unsupported function args: {args}"),
+            };
+            let bind = match bind {
+                Pattern::Tuple(tup) => tup.as_slice(),
+                _ => panic!("Unsupported function binders: {args}"),
+            };
+            y.p(rety).p(" ").p(name).p(" (");
+            for (idx, (bind, ty)) in bind.iter().zip(types).enumerate() {
+                if idx > 0 {
+                    y.p(", ");
+                }
+                // y.print("/* TODO: desugar pat match args */");
+                y.p(ty).p(" ").p(bind);
+            }
+            y.p(") ").p(body);
+        }
+    }
+    impl CLangify for Struct {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { name, gens: _, kind } = self;
+            y.p("struct ").p(name).nest(" {").p(kind);
+            y.endl().p("}");
+        }
+    }
+    impl CLangify for StructKind {
+        fn print(&self, y: &mut CLangifier) {
+            match self {
+                StructKind::Empty => y.endl().p("char _zero_sized_t;"),
+                StructKind::Tuple(k) => {
+                    for (idx, ty) in k.iter().enumerate() {
+                        y.endl().p(ty).p(" _").p(&idx).p(";");
+                    }
+                    y
+                }
+                StructKind::Struct(k) => y.p(k),
+            };
+        }
+    }
+    impl CLangify for StructMember {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { vis, name, ty } = self;
+            y.p(vis).p(ty).p(" ").p(name).p(";");
+        }
+    }
+    impl CLangify for Enum {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { name, gens: _, variants } = self;
+            y.nest("enum ").p(name).p(" {").endl();
+            for (idx, variant) in variants.iter().enumerate() {
+                if idx > 0 {
+                    y.p(",").endl();
+                }
+                y.p(variant);
+            }
+            y.endl().p("\n}");
+        }
+    }
+    impl CLangify for Variant {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { name, kind, body } = self;
+            y.p(name).p(kind).p(body);
+        }
+    }
+    impl CLangify for Impl {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { gens, target, body } = self;
+            y.nest("/* TODO: impl ").p(gens).p(target).p(" { */ ");
+            y.p(body);
+            y.p("/* } // impl ").p(target).p(" */ ");
+        }
+    }
+    impl CLangify for ImplKind {
+        fn print(&self, y: &mut CLangifier) {
+            match self {
+                ImplKind::Type(t) => y.p(t),
+                ImplKind::Trait { impl_trait, for_type } => {
+                    todo!("impl {impl_trait} for {for_type}")
+                }
+            };
+        }
+    }
+    impl CLangify for Use {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { absolute: _, tree } = self;
+            y.p(tree);
+        }
+    }
+    impl CLangify for UseTree {
+        fn print(&self, y: &mut CLangifier) {
+            match self {
+                UseTree::Tree(trees) => y.p(trees),
+                UseTree::Path(path, tree) => y.p("/* ").p(path).p(" */").p(tree),
+                UseTree::Alias(from, to) => y.p("#import <").p(from).p(">.h// ").p(to).p(" "),
+                UseTree::Name(name) => y.p("#import <").p(name).p(".h> "),
+                UseTree::Glob => y.p("/* TODO: use globbing */"),
+            };
+        }
+    }
+    impl CLangify for Block {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { stmts } = self;
+            {
+                let mut y = y.nest("{");
+                y.endl();
+                if let [
+                    stmts @ ..,
+                    Stmt { span: _, kind: StmtKind::Expr(expr), semi: Semi::Unterminated },
+                ] = stmts.as_slice()
+                {
+                    y.p(stmts).p("return ").p(expr).p(";");
+                } else {
+                    y.p(stmts);
+                }
+            }
+            y.endl().p("}");
+        }
+    }
+    impl CLangify for Stmt {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { span: _, kind, semi: _ } = self;
+            y.p(kind).p(";").endl();
+        }
+    }
+    impl CLangify for Semi {
+        fn print(&self, y: &mut CLangifier) {
+            y.p(";");
+        }
+    }
+    impl CLangify for StmtKind {
+        fn print(&self, y: &mut CLangifier) {
+            match self {
+                StmtKind::Empty => y,
+                StmtKind::Item(s) => y.p(s),
+                StmtKind::Expr(s) => y.p(s),
+            };
+        }
+    }
+    impl CLangify for Expr {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { span: _, kind } = self;
+            y.p(kind);
+        }
+    }
+    impl CLangify for ExprKind {
+        fn print(&self, y: &mut CLangifier) {
+            match self {
+                ExprKind::Closure(k) => todo!("Downgrade {k}"),
+                ExprKind::Quote(k) => k.print(y),
+                ExprKind::Let(k) => k.print(y),
+                ExprKind::Match(k) => k.print(y),
+                ExprKind::Assign(k) => k.print(y),
+                ExprKind::Modify(k) => k.print(y),
+                ExprKind::Binary(k) => k.print(y),
+                ExprKind::Unary(k) => k.print(y),
+                ExprKind::Cast(k) => k.print(y),
+                ExprKind::Member(k) => k.print(y),
+                ExprKind::Index(k) => k.print(y),
+                ExprKind::Structor(k) => k.print(y),
+                ExprKind::Path(k) => k.print(y),
+                ExprKind::Literal(k) => k.print(y),
+                ExprKind::Array(k) => k.print(y),
+                ExprKind::ArrayRep(k) => k.print(y),
+                ExprKind::AddrOf(k) => k.print(y),
+                ExprKind::Block(k) => k.print(y),
+                ExprKind::Empty => {}
+                ExprKind::Group(k) => k.print(y),
+                ExprKind::Tuple(k) => k.print(y),
+                ExprKind::While(k) => k.print(y),
+                ExprKind::If(k) => k.print(y),
+                ExprKind::For(k) => k.print(y),
+                ExprKind::Break(k) => k.print(y),
+                ExprKind::Return(k) => k.print(y),
+                ExprKind::Continue => {
+                    y.nest("continue");
+                }
+            }
+        }
+    }
+    impl CLangify for Quote {
+        fn print(&self, y: &mut CLangifier) {
+            y.nest("\"");
+            print!("{self}");
+            y.p("\"");
+        }
+    }
+    impl CLangify for Let {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { mutable, name, ty, init } = self;
+            let ty = ty.as_deref().map(|ty| &ty.kind).unwrap_or(&TyKind::Infer);
+            match ty {
+                TyKind::Array(TyArray { ty, count }) => {
+                    y.p(ty).p(" ").p(mutable).p(name).p("[").p(count).p("]");
+                }
+                TyKind::Fn(TyFn { args, rety }) => {
+                    y.nest("(").p(rety).p(" *").p(mutable).p(name).p(")(");
+                    match &args.kind {
+                        TyKind::Tuple(TyTuple { types }) => {
+                            for (idx, ty) in types.iter().enumerate() {
+                                if idx > 0 {
+                                    y.p(", ");
+                                }
+                                y.p(ty);
+                            }
+                        }
+                        _ => {
+                            y.p(args);
+                        }
+                    }
+                    y.p(")");
+                }
+                _ => {
+                    y.indent().p(ty).p(" ").p(mutable).p(name);
+                }
+            }
+            if let Some(init) = init {
+                y.p(" = ").p(init);
+            }
+        }
+    }
+
+    impl CLangify for Pattern {
+        fn print(&self, y: &mut CLangifier) {
+            // TODO: Pattern match desugaring!!!
+            match self {
+                Pattern::Name(name) => y.p(name),
+                Pattern::Path(path) => y.p(path),
+                Pattern::Literal(literal) => y.p(literal),
+                Pattern::Rest(name) => y.p("..").p(name),
+                Pattern::Ref(mutability, pattern) => y.p("&").p(mutability).p(pattern),
+                Pattern::RangeExc(head, tail) => y.p("RangeExc").p(head).p(tail),
+                Pattern::RangeInc(head, tail) => y.p("RangeExc").p(head).p(tail),
+                Pattern::Tuple(patterns) => y.nest("Tuple").p(patterns),
+                Pattern::Array(patterns) => y.nest("Array").p(patterns),
+                Pattern::Struct(path, items) => {
+                    {
+                        let mut y = y.nest("Struct");
+                        y.p(path);
+                        for (name, item) in items {
+                            y.p(name).p(item);
+                        }
+                    }
+                    y
+                }
+                Pattern::TupleStruct(path, items) => {
+                    {
+                        let mut y = y.nest("TupleStruct");
+                        y.p(path).p(items);
+                    }
+                    y
+                }
+            };
+        }
+    }
+    impl CLangify for Match {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { scrutinee, arms } = self;
+            y.p("/* match ").p(scrutinee);
+            y.nest(" { ").p(arms);
+            y.p(" } */");
+        }
+    }
+
+    impl CLangify for MatchArm {
+        fn print(&self, y: &mut CLangifier) {
+            let Self(pat, expr) = self;
+            y.p(pat).p(" => ").p(expr).p(", ");
+        }
+    }
+    impl CLangify for Assign {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { parts } = self;
+            y.p(&parts.0).p(" = ").p(&parts.1);
+        }
+    }
+    impl CLangify for Modify {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { kind, parts } = self;
+            y.p(&parts.0).p(kind).p(&parts.1);
+        }
+    }
+    impl CLangify for ModifyKind {
+        fn print(&self, _y: &mut CLangifier) {
+            print!(" {self} ");
+        }
+    }
+    impl CLangify for Binary {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { kind, parts } = self;
+            match kind {
+                BinaryKind::Call => y.p(&parts.0).p(&parts.1),
+                _ => y.p("(").p(&parts.0).p(kind).p(&parts.1).p(")"),
+            };
+        }
+    }
+    impl CLangify for BinaryKind {
+        fn print(&self, _y: &mut CLangifier) {
+            print!(" {self} ");
+        }
+    }
+    impl CLangify for Unary {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { kind, tail } = self;
+            match kind {
+                UnaryKind::Deref => y.p("*").p(tail),
+                UnaryKind::Neg => y.p("-").p(tail),
+                UnaryKind::Not => y.p("!").p(tail),
+                UnaryKind::RangeInc => todo!("Unary RangeInc in C"),
+                UnaryKind::RangeExc => todo!("Unary RangeExc in C"),
+                UnaryKind::Loop => y.nest("while (1) { ").p(tail).p(" }"),
+                UnaryKind::At => todo!(),
+                UnaryKind::Tilde => todo!(),
+            };
+        }
+    }
+    impl CLangify for Cast {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { head, ty } = self;
+            y.nest("(").p(ty).p(")");
+            y.p(head);
+        }
+    }
+    impl CLangify for Member {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { head, kind } = self;
+            match kind {
+                MemberKind::Call(name, Tuple { exprs }) => {
+                    y.p(name);
+                    y.p("(");
+                    for (idx, expr) in iter::once(head.as_ref()).chain(exprs).enumerate() {
+                        if idx > 0 {
+                            y.p(", ");
+                        }
+                        y.p(expr);
+                    }
+                    y.p(")")
+                }
+                MemberKind::Struct(name) => y.p(head).p(".").p(name),
+                MemberKind::Tuple(idx) => y.p(head).p("._").p(idx),
+            };
+        }
+    }
+    impl CLangify for Tuple {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { exprs } = self;
+            let mut y = y.nest("( ");
+            for (idx, expr) in exprs.iter().enumerate() {
+                if idx > 0 {
+                    y.p(", ");
+                }
+                y.p(expr);
+            }
+            y.p(" )");
+        }
+    }
+    impl CLangify for Index {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { head, indices } = self;
+            y.p(head);
+            for index in indices {
+                y.p("[").p(index).p("]");
+            }
+        }
+    }
+    impl CLangify for Structor {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { to, init } = self;
+            y.nest("(").p(to).p(")");
+            {
+                let mut y = y.nest("{ ");
+                for (idx, field) in init.iter().enumerate() {
+                    if idx > 0 {
+                        y.p(", ");
+                    }
+                    y.p(field);
+                }
+                y.p(init);
+            }
+            y.p("}");
+        }
+    }
+    impl CLangify for Fielder {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { name, init } = self;
+            y.p(".").p(name).p(" = ").p(init);
+        }
+    }
+    impl CLangify for Array {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { values } = self;
+            {
+                let mut y = y.nest("{");
+                y.endl();
+                for (idx, value) in values.iter().enumerate() {
+                    if idx > 0 {
+                        y.p(", ");
+                    }
+                    y.p(value);
+                }
+            }
+            y.endl().p("}");
+        }
+    }
+    impl CLangify for ArrayRep {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { value, repeat } = self;
+            let ExprKind::Literal(Literal::Int(repeat)) = &repeat.kind else {
+                eprintln!("Constant needs folding: {repeat}");
+                return;
+            };
+            {
+                let mut y = y.nest("{");
+                for _ in 0..*repeat {
+                    y.endl().p(value).p(",");
+                }
+            }
+            y.endl().p("}");
+        }
+    }
+    impl CLangify for AddrOf {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { mutable: _, expr } = self;
+            y.p("&").p(expr);
+        }
+    }
+    impl CLangify for Group {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { expr } = self;
+            y.p("(").p(expr).p(")");
+        }
+    }
+    impl CLangify for While {
+        fn print(&self, y: &mut CLangifier) {
+            // TODO: to properly propagate intermediate values, a new temp variable needs to be
+            // declared on every line lmao. This will require type info.
+            let Self { cond, pass, fail } = self;
+            let Else { body: fail } = fail;
+            y.nest("while(1) {")
+                .endl()
+                .p("if (")
+                .p(cond)
+                .p(") ")
+                .p(pass);
+            {
+                let mut y = y.nest(" else {");
+                y.endl();
+                if let Some(fail) = fail {
+                    y.p(fail).p(";").endl();
+                }
+                y.p("break;");
+            }
+            y.endl().p("}");
+        }
+    }
+    impl CLangify for Else {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { body } = self;
+            if let Some(body) = body {
+                y.p(" else ").p(body);
+            }
+        }
+    }
+    impl CLangify for If {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { cond, pass, fail } = self;
+            y.p("if (").p(cond).p(")");
+            y.p(pass).p(fail);
+        }
+    }
+    impl CLangify for For {
+        #[rustfmt::skip]
+        fn print(&self, y: &mut CLangifier) {
+            let Self { bind, cond, pass, fail: _ } = self;
+            let (mode, (head, tail)) = match &cond.kind {
+                ExprKind::Binary(Binary { kind: BinaryKind::RangeExc, parts }) => (false, &**parts),
+                ExprKind::Binary(Binary { kind: BinaryKind::RangeInc, parts }) => (true, &**parts),
+                _ => todo!("Clangify for loops"),
+            };
+            // for (int bind = head; bind mode? < : <= tail; bind++);
+            y.p("for ( int ").p(bind).p(" = ").p(head).p("; ");
+            y.p(bind).p(if mode {"<="} else {"<"}).p(tail).p("; ");
+            y.p("++").p(bind).p(" ) ").p(pass);
+
+        }
+    }
+    impl CLangify for Break {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { body } = self;
+            y.nest("break ").p(body);
+        }
+    }
+    impl CLangify for Return {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { body } = self;
+            y.nest("return ").p(body);
+        }
+    }
+    impl CLangify for Literal {
+        fn print(&self, y: &mut CLangifier) {
+            match self {
+                Literal::Float(l) => y.p(l),
+                Literal::Bool(l) => y.p(l),
+                Literal::Int(l) => y.p(l),
+                Literal::Char(l) => y.p("'").p(l).p("'"),
+                Literal::String(l) => y.p(&'"').p(l).p(&'"'),
+            };
+        }
+    }
+    impl CLangify for Sym {
+        fn print(&self, y: &mut CLangifier) {
+            y.p(self.to_ref());
+        }
+    }
+    impl CLangify for Ty {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { span: _, kind, gens: _ } = self;
+            y.p(kind);
+        }
+    }
+    impl CLangify for TyKind {
+        fn print(&self, y: &mut CLangifier) {
+            match self {
+                TyKind::Never => y.p("Never"),
+                TyKind::Infer => y.p("auto"),
+                TyKind::Path(t) => y.p(t),
+                TyKind::Tuple(t) => y.p(t),
+                TyKind::Ref(t) => y.p(t),
+                TyKind::Ptr(t) => y.p(t),
+                TyKind::Fn(t) => y.p(t),
+                TyKind::Slice(t) => y.p(t),
+                TyKind::Array(t) => y.p(t),
+            };
+        }
+    }
+    impl CLangify for Path {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { absolute: _, parts } = self;
+            for (idx, part) in parts.iter().enumerate() {
+                if idx > 0 {
+                    y.p("_");
+                }
+                y.p(part);
+            }
+        }
+    }
+    impl CLangify for PathPart {
+        fn print(&self, y: &mut CLangifier) {
+            match self {
+                PathPart::SuperKw => y.p("super"),
+                PathPart::SelfTy => y.p("Self"),
+                PathPart::Ident(i) => y.p(i),
+            };
+        }
+    }
+    impl CLangify for TyArray {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { ty, count } = self;
+            y.p(ty).p("[").p(count).p("]");
+        }
+    }
+    impl CLangify for TySlice {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { ty } = self;
+            y.p(ty).p("* ");
+        }
+    }
+    impl CLangify for TyTuple {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { types } = self;
+            {
+                let mut y = y.nest("struct {");
+                y.endl();
+                for (idx, ty) in types.iter().enumerate() {
+                    if idx > 0 {
+                        y.p(",").endl();
+                    }
+                    y.p(ty);
+                }
+            }
+            y.endl().p("}");
+        }
+    }
+    impl CLangify for TyRef {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { count, mutable, to } = self;
+            y.p(mutable).p(to);
+            for _ in 0..*count {
+                y.p("*");
+            }
+        }
+    }
+    impl CLangify for TyPtr {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { to } = self;
+            y.p(to).p("*");
+        }
+    }
+    impl CLangify for TyFn {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { args, rety } = self;
+            // TODO: function pointer syntax
+            y.nest("(").p(rety).p(" *)(");
+            match &args.kind {
+                TyKind::Tuple(TyTuple { types }) => {
+                    for (idx, ty) in types.iter().enumerate() {
+                        if idx > 0 {
+                            y.p(", ");
+                        }
+                        y.p(ty);
+                    }
+                    y
+                }
+                _ => y.p(args),
+            }
+            .p(")");
+        }
+    }
+
+    impl<T: CLangify> CLangify for Option<T> {
+        fn print(&self, y: &mut CLangifier) {
+            if let Some(v) = self {
+                y.p(v);
+            }
+        }
+    }
+    impl<T: CLangify> CLangify for Box<T> {
+        fn print(&self, y: &mut CLangifier) {
+            y.p(&**self);
+        }
+    }
+    impl<T: CLangify> CLangify for Vec<T> {
+        fn print(&self, y: &mut CLangifier) {
+            for thing in self {
+                y.p(thing);
+            }
+        }
+    }
+    impl<T: CLangify> CLangify for [T] {
+        fn print(&self, y: &mut CLangifier) {
+            for thing in self {
+                y.p(thing);
+            }
+        }
+    }
+    impl CLangify for () {
+        fn print(&self, _y: &mut CLangifier) {
+            // TODO: C has no language support for zst
+        }
+    }
+
+    impl<T: CLangify> CLangify for &T {
+        fn print(&self, y: &mut CLangifier) {
+            (*self).print(y)
+        }
+    }
+
+    impl CLangify for std::fmt::Arguments<'_> {
+        fn print(&self, _y: &mut CLangifier) {
+            print!("{self}")
+        }
+    }
+    macro_rules! scalar {
+        ($($t:ty),*$(,)?) => {
+            $(impl CLangify for $t {
+                fn print(&self, _y: &mut CLangifier) {
+                    print!("{self}");
+                }
+            })*
+        };
+    }
+
+    scalar! {
+        bool, char, u8, u16, u32, u64, u128, usize, i8, i16, i32, i64, i128, isize, str, &str, String
+    }
+}

compiler/cl-repl/examples/yaml.rs

@@ -1,8 +1,9 @@
 //! Pretty prints a conlang AST in yaml
 
+use cl_ast::Stmt;
 use cl_lexer::Lexer;
 use cl_parser::Parser;
-use cl_repl::repline::{error::Error as RlError, Repline};
+use repline::{Repline, error::Error as RlError};
 use std::error::Error;
 
 fn main() -> Result<(), Box<dyn Error>> {
@@ -18,8 +19,8 @@ fn main() -> Result<(), Box<dyn Error>> {
             Err(e) => Err(e)?,
         };
 
-        let mut parser = Parser::new(Lexer::new(&line));
-        let code = match parser.stmt() {
+        let mut parser = Parser::new("", Lexer::new(&line));
+        let code = match parser.parse::<Stmt>() {
             Ok(code) => {
                 rl.accept();
                 code
@@ -40,7 +41,6 @@ pub use yamler::Yamler;
 pub mod yamler {
     use crate::yamlify::Yamlify;
     use std::{
-        fmt::Display,
         io::Write,
         ops::{Deref, DerefMut},
     };
@@ -54,7 +54,7 @@ pub mod yamler {
             Self::default()
         }
 
-        pub fn indent(&mut self) -> Section {
+        pub fn indent(&mut self) -> Section<'_> {
             Section::new(self)
         }
 
@@ -80,28 +80,33 @@ pub mod yamler {
         }
 
         /// Prints a section header and increases indentation
-        pub fn key(&mut self, name: impl Display) -> Section {
+        pub fn key(&mut self, name: impl Yamlify) -> Section<'_> {
             println!();
             self.print_indentation(&mut std::io::stdout().lock());
-            print!("- {name}:");
+            print!("  ");
+            name.yaml(self);
+            print!(":");
             self.indent()
         }
 
         /// Prints a yaml key value pair: `- name: "value"`
-        pub fn pair<D: Display, T: Yamlify>(&mut self, name: D, value: T) -> &mut Self {
-            self.key(name).yaml(&value);
+        pub fn pair<D: Yamlify, T: Yamlify>(&mut self, name: D, value: T) -> &mut Self {
+            self.key(name).value(value);
             self
         }
 
         /// Prints a yaml scalar value: `"name"``
-        pub fn value<D: Display>(&mut self, value: D) -> &mut Self {
-            print!(" {value}");
+        pub fn value<D: Yamlify>(&mut self, value: D) -> &mut Self {
+            print!(" ");
+            value.yaml(self);
             self
         }
 
         pub fn list<D: Yamlify>(&mut self, list: &[D]) -> &mut Self {
-            for (idx, value) in list.iter().enumerate() {
-                self.pair(idx, value);
+            for value in list {
+                println!();
+                self.print_indentation(&mut std::io::stdout().lock());
+                self.yaml(&"- ").yaml(value);
             }
             self
         }
@@ -119,19 +124,19 @@ pub mod yamler {
         }
     }
 
-    impl<'y> Deref for Section<'y> {
+    impl Deref for Section<'_> {
         type Target = Yamler;
         fn deref(&self) -> &Self::Target {
             self.yamler
         }
     }
-    impl<'y> DerefMut for Section<'y> {
+    impl DerefMut for Section<'_> {
         fn deref_mut(&mut self) -> &mut Self::Target {
             self.yamler
         }
     }
 
-    impl<'y> Drop for Section<'y> {
+    impl Drop for Section<'_> {
         fn drop(&mut self) {
             let Self { yamler } = self;
             yamler.decrease();
@@ -149,8 +154,8 @@ pub mod yamlify {
 
     impl Yamlify for File {
         fn yaml(&self, y: &mut Yamler) {
-            let File { items } = self;
-            y.key("File").yaml(items);
+            let File { name, items } = self;
+            y.key("File").pair("name", name).yaml(items);
         }
     }
     impl Yamlify for Visibility {
@@ -192,7 +197,7 @@ pub mod yamlify {
 
     impl Yamlify for Item {
         fn yaml(&self, y: &mut Yamler) {
-            let Self { extents: _, attrs, vis, kind } = self;
+            let Self { span: _, attrs, vis, kind } = self;
             y.key("Item").yaml(attrs).yaml(vis).yaml(kind);
         }
     }
@@ -207,13 +212,20 @@ pub mod yamlify {
                 ItemKind::Struct(f) => y.yaml(f),
                 ItemKind::Enum(f) => y.yaml(f),
                 ItemKind::Impl(f) => y.yaml(f),
+                ItemKind::Use(f) => y.yaml(f),
             };
         }
     }
+    impl Yamlify for Generics {
+        fn yaml(&self, y: &mut Yamler) {
+            let Self { vars } = self;
+            y.key("Generics").value(vars);
+        }
+    }
     impl Yamlify for Alias {
         fn yaml(&self, y: &mut Yamler) {
-            let Self { to, from } = self;
-            y.key("Alias").pair("to", to).pair("from", from);
+            let Self { name, from } = self;
+            y.key("Alias").pair("to", name).pair("from", from);
         }
     }
     impl Yamlify for Const {
@@ -233,32 +245,28 @@ pub mod yamlify {
     }
     impl Yamlify for Module {
         fn yaml(&self, y: &mut Yamler) {
-            let Self { name, kind } = self;
-            y.key("Module").pair("name", name).yaml(kind);
-        }
-    }
-    impl Yamlify for ModuleKind {
-        fn yaml(&self, y: &mut Yamler) {
-            match self {
-                ModuleKind::Inline(f) => y.yaml(f),
-                ModuleKind::Outline => y,
-            };
+            let Self { name, file } = self;
+            y.key("Module").pair("name", name).yaml(file);
         }
     }
     impl Yamlify for Function {
         fn yaml(&self, y: &mut Yamler) {
-            let Self { name, args, body, rety } = self;
+            let Self { name, gens, sign, bind, body } = self;
             y.key("Function")
                 .pair("name", name)
-                .pair("args", args)
-                .pair("body", body)
-                .pair("rety", rety);
+                .pair("gens", gens)
+                .pair("sign", sign)
+                .pair("bind", bind)
+                .pair("body", body);
         }
     }
     impl Yamlify for Struct {
         fn yaml(&self, y: &mut Yamler) {
-            let Self { name, kind } = self;
-            y.key("Struct").pair("name", name).yaml(kind);
+            let Self { name, gens, kind } = self;
+            y.key("Struct")
+                .pair("gens", gens)
+                .pair("name", name)
+                .yaml(kind);
         }
     }
     impl Yamlify for StructKind {
@@ -278,38 +286,56 @@ pub mod yamlify {
     }
     impl Yamlify for Enum {
         fn yaml(&self, y: &mut Yamler) {
-            let Self { name, kind } = self;
-            y.key("Enum").pair("name", name).yaml(kind);
-        }
-    }
-    impl Yamlify for EnumKind {
-        fn yaml(&self, y: &mut Yamler) {
-            match self {
-                EnumKind::NoVariants => y,
-                EnumKind::Variants(v) => y.yaml(v),
-            };
+            let Self { name, gens, variants: kind } = self;
+            y.key("Enum")
+                .pair("gens", gens)
+                .pair("name", name)
+                .yaml(kind);
         }
     }
     impl Yamlify for Variant {
         fn yaml(&self, y: &mut Yamler) {
-            let Self { name, kind } = self;
-            y.key("Variant").pair("name", name).yaml(kind);
-        }
-    }
-    impl Yamlify for VariantKind {
-        fn yaml(&self, y: &mut Yamler) {
-            match self {
-                VariantKind::Plain => y,
-                VariantKind::CLike(v) => y.yaml(v),
-                VariantKind::Tuple(v) => y.yaml(v),
-                VariantKind::Struct(v) => y.yaml(v),
-            };
+            let Self { name, kind, body } = self;
+            y.key("Variant")
+                .pair("name", name)
+                .pair("kind", kind)
+                .pair("body", body);
         }
     }
     impl Yamlify for Impl {
         fn yaml(&self, y: &mut Yamler) {
-            let Self { target, body } = self;
-            y.key("Impl").pair("target", target).pair("body", body);
+            let Self { gens, target, body } = self;
+            y.key("Impl")
+                .pair("gens", gens)
+                .pair("target", target)
+                .pair("body", body);
+        }
+    }
+    impl Yamlify for ImplKind {
+        fn yaml(&self, y: &mut Yamler) {
+            match self {
+                ImplKind::Type(t) => y.value(t),
+                ImplKind::Trait { impl_trait, for_type } => {
+                    y.pair("trait", impl_trait).pair("for_type", for_type)
+                }
+            };
+        }
+    }
+    impl Yamlify for Use {
+        fn yaml(&self, y: &mut Yamler) {
+            let Self { absolute, tree } = self;
+            y.key("Use").pair("absolute", absolute).yaml(tree);
+        }
+    }
+    impl Yamlify for UseTree {
+        fn yaml(&self, y: &mut Yamler) {
+            match self {
+                UseTree::Tree(trees) => y.pair("trees", trees),
+                UseTree::Path(path, tree) => y.pair("path", path).pair("tree", tree),
+                UseTree::Alias(from, to) => y.pair("from", from).pair("to", to),
+                UseTree::Name(name) => y.pair("name", name),
+                UseTree::Glob => y.value("Glob"),
+            };
         }
     }
     impl Yamlify for Block {
@@ -320,8 +346,8 @@ pub mod yamlify {
     }
     impl Yamlify for Stmt {
         fn yaml(&self, y: &mut Yamler) {
-            let Self { extents: _, kind, semi } = self;
-            y.key("Stmt").yaml(kind).yaml(semi);
+            let Self { span: _, kind, semi } = self;
+            y.key("Stmt").value(kind).yaml(semi);
         }
     }
     impl Yamlify for Semi {
@@ -335,35 +361,32 @@ pub mod yamlify {
         fn yaml(&self, y: &mut Yamler) {
             match self {
                 StmtKind::Empty => y,
-                StmtKind::Local(s) => y.yaml(s),
                 StmtKind::Item(s) => y.yaml(s),
                 StmtKind::Expr(s) => y.yaml(s),
             };
         }
     }
-    impl Yamlify for Let {
-        fn yaml(&self, y: &mut Yamler) {
-            let Self { mutable, name, ty, init } = self;
-            y.key("Let")
-                .pair("name", name)
-                .yaml(mutable)
-                .pair("ty", ty)
-                .pair("init", init);
-        }
-    }
     impl Yamlify for Expr {
         fn yaml(&self, y: &mut Yamler) {
-            let Self { extents: _, kind } = self;
+            let Self { span: _, kind } = self;
             y.yaml(kind);
         }
     }
     impl Yamlify for ExprKind {
         fn yaml(&self, y: &mut Yamler) {
             match self {
+                ExprKind::Closure(k) => k.yaml(y),
+                ExprKind::Quote(k) => k.yaml(y),
+                ExprKind::Let(k) => k.yaml(y),
+                ExprKind::Match(k) => k.yaml(y),
                 ExprKind::Assign(k) => k.yaml(y),
+                ExprKind::Modify(k) => k.yaml(y),
                 ExprKind::Binary(k) => k.yaml(y),
                 ExprKind::Unary(k) => k.yaml(y),
+                ExprKind::Cast(k) => k.yaml(y),
+                ExprKind::Member(k) => k.yaml(y),
                 ExprKind::Index(k) => k.yaml(y),
+                ExprKind::Structor(k) => k.yaml(y),
                 ExprKind::Path(k) => k.yaml(y),
                 ExprKind::Literal(k) => k.yaml(y),
                 ExprKind::Array(k) => k.yaml(y),
@@ -378,22 +401,99 @@ pub mod yamlify {
                 ExprKind::For(k) => k.yaml(y),
                 ExprKind::Break(k) => k.yaml(y),
                 ExprKind::Return(k) => k.yaml(y),
-                ExprKind::Continue(k) => k.yaml(y),
+                ExprKind::Continue => {
+                    y.key("Continue");
+                }
             }
         }
     }
+    impl Yamlify for Closure {
+        fn yaml(&self, y: &mut Yamler) {
+            let Self { arg, body } = self;
+            y.key("Closure").pair("arg", arg).pair("body", body);
+        }
+    }
+    impl Yamlify for Quote {
+        fn yaml(&self, y: &mut Yamler) {
+            y.key("Quote").value(self);
+        }
+    }
+    impl Yamlify for Let {
+        fn yaml(&self, y: &mut Yamler) {
+            let Self { mutable, name, ty, init } = self;
+            y.key("Let")
+                .pair("name", name)
+                .yaml(mutable)
+                .pair("ty", ty)
+                .pair("init", init);
+        }
+    }
+
+    impl Yamlify for Pattern {
+        fn yaml(&self, y: &mut Yamler) {
+            match self {
+                Pattern::Name(name) => y.value(name),
+                Pattern::Path(path) => y.value(path),
+                Pattern::Literal(literal) => y.value(literal),
+                Pattern::Rest(name) => y.pair("Rest", name),
+                Pattern::Ref(mutability, pattern) => y.yaml(mutability).pair("Pat", pattern),
+                Pattern::RangeInc(head, tail) => {
+                    y.key("RangeInc").pair("head", head).pair("tail", tail);
+                    y
+                }
+                Pattern::RangeExc(head, tail) => {
+                    y.key("RangeExc").pair("head", head).pair("tail", tail);
+                    y
+                }
+                Pattern::Tuple(patterns) => y.key("Tuple").list(patterns),
+                Pattern::Array(patterns) => y.key("Array").list(patterns),
+                Pattern::Struct(path, items) => {
+                    {
+                        let mut y = y.key("Struct");
+                        y.yaml(path);
+                        for (name, item) in items {
+                            y.pair(name, item);
+                        }
+                    }
+                    y
+                }
+                Pattern::TupleStruct(path, items) => {
+                    y.key("TupleStruct").yaml(path).list(items);
+                    y
+                }
+            };
+        }
+    }
+    impl Yamlify for Match {
+        fn yaml(&self, y: &mut Yamler) {
+            let Self { scrutinee, arms } = self;
+            y.key("Match")
+                .pair("scrutinee", scrutinee)
+                .pair("arms", arms);
+        }
+    }
+
+    impl Yamlify for MatchArm {
+        fn yaml(&self, y: &mut Yamler) {
+            let Self(pat, expr) = self;
+            y.pair("pat", pat).pair("expr", expr);
+        }
+    }
     impl Yamlify for Assign {
         fn yaml(&self, y: &mut Yamler) {
-            let Self { kind, parts } = self;
+            let Self { parts } = self;
             y.key("Assign")
-                .pair("kind", kind)
                 .pair("head", &parts.0)
                 .pair("tail", &parts.1);
         }
     }
-    impl Yamlify for AssignKind {
+    impl Yamlify for Modify {
         fn yaml(&self, y: &mut Yamler) {
-            y.value(self);
+            let Self { kind, parts } = self;
+            y.key("Modify")
+                .pair("kind", kind)
+                .pair("head", &parts.0)
+                .pair("tail", &parts.1);
         }
     }
     impl Yamlify for Binary {
@@ -405,20 +505,31 @@ pub mod yamlify {
                 .pair("tail", &parts.1);
         }
     }
-    impl Yamlify for BinaryKind {
-        fn yaml(&self, y: &mut Yamler) {
-            y.value(self);
-        }
-    }
     impl Yamlify for Unary {
         fn yaml(&self, y: &mut Yamler) {
             let Self { kind, tail } = self;
             y.key("Unary").pair("kind", kind).pair("tail", tail);
         }
     }
-    impl Yamlify for UnaryKind {
+    impl Yamlify for Cast {
         fn yaml(&self, y: &mut Yamler) {
-            y.value(self);
+            let Self { head, ty } = self;
+            y.key("Cast").pair("head", head).pair("ty", ty);
+        }
+    }
+    impl Yamlify for Member {
+        fn yaml(&self, y: &mut Yamler) {
+            let Self { head, kind } = self;
+            y.key("Member").pair("head", head).pair("kind", kind);
+        }
+    }
+    impl Yamlify for MemberKind {
+        fn yaml(&self, y: &mut Yamler) {
+            match self {
+                MemberKind::Call(id, args) => y.pair("id", id).pair("args", args),
+                MemberKind::Struct(id) => y.pair("id", id),
+                MemberKind::Tuple(id) => y.pair("id", id),
+            };
         }
     }
     impl Yamlify for Tuple {
@@ -430,7 +541,22 @@ pub mod yamlify {
     impl Yamlify for Index {
         fn yaml(&self, y: &mut Yamler) {
             let Self { head, indices } = self;
-            y.key("Index").pair("head", head).list(indices);
+            y.key("Index")
+                .pair("head", head)
+                .key("indices")
+                .list(indices);
+        }
+    }
+    impl Yamlify for Structor {
+        fn yaml(&self, y: &mut Yamler) {
+            let Self { to, init } = self;
+            y.key("Structor").pair("to", to).list(init);
+        }
+    }
+    impl Yamlify for Fielder {
+        fn yaml(&self, y: &mut Yamler) {
+            let Self { name, init } = self;
+            y.key("Fielder").pair("name", name).pair("init", init);
         }
     }
     impl Yamlify for Array {
@@ -449,11 +575,8 @@ pub mod yamlify {
     }
     impl Yamlify for AddrOf {
         fn yaml(&self, y: &mut Yamler) {
-            let Self { count, mutable, expr } = self;
-            y.key("AddrOf")
-                .yaml(mutable)
-                .pair("count", count)
-                .pair("expr", expr);
+            let Self { mutable, expr } = self;
+            y.key("AddrOf").yaml(mutable).pair("expr", expr);
         }
     }
     impl Yamlify for Group {
@@ -468,13 +591,13 @@ pub mod yamlify {
             y.key("While")
                 .pair("cond", cond)
                 .pair("pass", pass)
-                .pair("fail", fail);
+                .yaml(fail);
         }
     }
     impl Yamlify for Else {
         fn yaml(&self, y: &mut Yamler) {
             let Self { body } = self;
-            y.key("Else").yaml(body);
+            y.key("fail").yaml(body);
         }
     }
     impl Yamlify for If {
@@ -505,47 +628,35 @@ pub mod yamlify {
             y.key("Return").yaml(body);
         }
     }
-    impl Yamlify for Continue {
-        fn yaml(&self, y: &mut Yamler) {
-            y.key("Continue");
-        }
-    }
     impl Yamlify for Literal {
-        fn yaml(&self, y: &mut Yamler) {
-            y.value(format_args!("\"{self}\""));
-        }
-    }
-    impl Yamlify for Identifier {
-        fn yaml(&self, y: &mut Yamler) {
-            let Self(name) = self;
-            y.value(name);
-        }
-    }
-    impl Yamlify for Param {
-        fn yaml(&self, y: &mut Yamler) {
-            let Self { mutability, name, ty } = self;
-            y.key("Param")
-                .yaml(mutability)
-                .pair("name", name)
-                .pair("ty", ty);
+        fn yaml(&self, _y: &mut Yamler) {
+            match self {
+                Literal::Bool(v) => print!("{v}"),
+                Literal::Char(v) => print!("'{}'", v.escape_debug()),
+                Literal::Int(v) => print!("{v}"),
+                Literal::Float(v) => print!("{v}"),
+                Literal::String(v) => print!("{}", v.escape_debug()),
+            }
         }
     }
     impl Yamlify for Ty {
         fn yaml(&self, y: &mut Yamler) {
-            let Self { extents: _, kind } = self;
-            y.key("Ty").yaml(kind);
+            let Self { span: _, kind, gens } = self;
+            y.key("Ty").yaml(kind).yaml(gens);
         }
     }
     impl Yamlify for TyKind {
         fn yaml(&self, y: &mut Yamler) {
             match self {
                 TyKind::Never => y.value("Never"),
-                TyKind::Empty => y.value("Empty"),
-                TyKind::SelfTy => y.value("Self"),
+                TyKind::Infer => y.value("_"),
                 TyKind::Path(t) => y.yaml(t),
                 TyKind::Tuple(t) => y.yaml(t),
                 TyKind::Ref(t) => y.yaml(t),
+                TyKind::Ptr(t) => y.yaml(t),
                 TyKind::Fn(t) => y.yaml(t),
+                TyKind::Slice(t) => y.yaml(t),
+                TyKind::Array(t) => y.yaml(t),
             };
         }
     }
@@ -556,20 +667,30 @@ pub mod yamlify {
             if *absolute {
                 y.pair("absolute", absolute);
             }
-            for part in parts {
-                y.pair("part", part);
-            }
+            y.yaml(parts);
         }
     }
     impl Yamlify for PathPart {
         fn yaml(&self, y: &mut Yamler) {
             match self {
                 PathPart::SuperKw => y.value("super"),
-                PathPart::SelfKw => y.value("self"),
+                PathPart::SelfTy => y.value("Self"),
                 PathPart::Ident(i) => y.yaml(i),
             };
         }
     }
+    impl Yamlify for TyArray {
+        fn yaml(&self, y: &mut Yamler) {
+            let Self { ty, count } = self;
+            y.key("TyArray").pair("ty", ty).pair("count", count);
+        }
+    }
+    impl Yamlify for TySlice {
+        fn yaml(&self, y: &mut Yamler) {
+            let Self { ty } = self;
+            y.key("TyArray").pair("ty", ty);
+        }
+    }
     impl Yamlify for TyTuple {
         fn yaml(&self, y: &mut Yamler) {
             let Self { types } = self;
@@ -581,8 +702,17 @@ pub mod yamlify {
     }
     impl Yamlify for TyRef {
         fn yaml(&self, y: &mut Yamler) {
-            let Self { count, to } = self;
-            y.key("TyRef").pair("count", count).pair("to", to);
+            let Self { count, mutable, to } = self;
+            y.key("TyRef")
+                .pair("count", count)
+                .yaml(mutable)
+                .pair("to", to);
+        }
+    }
+    impl Yamlify for TyPtr {
+        fn yaml(&self, y: &mut Yamler) {
+            let Self { to } = self;
+            y.key("TyPtr").pair("to", to);
         }
     }
     impl Yamlify for TyFn {
@@ -608,9 +738,7 @@ pub mod yamlify {
     }
     impl<T: Yamlify> Yamlify for Vec<T> {
         fn yaml(&self, y: &mut Yamler) {
-            for thing in self {
-                y.yaml(thing);
-            }
+            y.list(self);
         }
     }
     impl Yamlify for () {
@@ -626,14 +754,15 @@ pub mod yamlify {
     macro_rules! scalar {
         ($($t:ty),*$(,)?) => {
             $(impl Yamlify for $t {
-                fn yaml(&self, y: &mut Yamler) {
-                    y.value(self);
+                fn yaml(&self, _y: &mut Yamler) {
+                    print!("{self}");
                 }
             })*
         };
     }
 
     scalar! {
-        bool, char, u8, u16, u32, u64, u128, usize, i8, i16, i32, i64, i128, isize, &str, String
+        bool, char, u8, u16, u32, u64, u128, usize, i8, i16, i32, i64, i128, isize, &str, String,
+        BinaryKind, UnaryKind, ModifyKind, Sym,
     }
 }

compiler/cl-repl/src/ansi.rs

@@ -0,0 +1,14 @@
+//! ANSI escape sequences
+
+pub const RED: &str = "\x1b[31m";
+pub const GREEN: &str = "\x1b[32m"; // the color of type checker mode
+pub const CYAN: &str = "\x1b[36m";
+pub const BRIGHT_GREEN: &str = "\x1b[92m";
+pub const BRIGHT_BLUE: &str = "\x1b[94m";
+pub const BRIGHT_MAGENTA: &str = "\x1b[95m";
+pub const BRIGHT_CYAN: &str = "\x1b[96m";
+pub const RESET: &str = "\x1b[0m";
+pub const OUTPUT: &str = "\x1b[38;5;117m";
+
+pub const CLEAR_LINES: &str = "\x1b[G\x1b[J";
+pub const CLEAR_ALL: &str = "\x1b[H\x1b[2J\x1b[3J";

compiler/cl-repl/src/args.rs

@@ -0,0 +1,68 @@
+//! Handles argument parsing (currently using the [argwerk] crate)
+
+use std::{io::IsTerminal, path::PathBuf, str::FromStr};
+
+argwerk::define! {
+    ///
+    ///The Conlang prototype debug interface
+    #[usage = "conlang [<file>] [-I <include...>] [-m <mode>] [-r <repl>]"]
+    #[derive(Clone, PartialEq, Eq, PartialOrd, Ord)]
+    pub struct Args {
+        pub file: Option<PathBuf>,
+        pub include: Vec<PathBuf>,
+        pub mode: Mode,
+        pub repl: bool = is_terminal(),
+    }
+
+    ///files to include
+    ["-I" | "--include", path] => {
+        include.push(path.into());
+    }
+    ///the CLI operating mode (`f`mt | `l`ex | `r`un)
+    ["-m" | "--mode", flr] => {
+        mode = flr.parse()?;
+    }
+    ///whether to start the repl (`true` or `false`)
+    ["-r" | "--repl", bool] => {
+        repl = bool.parse()?;
+    }
+    ///display usage information
+    ["-h" | "--help"] => {
+        println!("{}", Args::help());
+        if true { std::process::exit(0); }
+    }
+    ///the main source file
+    [#[option] path] if file.is_none() => {
+        file = path.map(Into::into);
+    }
+
+    [path] if file.is_some() => {
+        include.push(path.into());
+    }
+}
+
+/// gets whether stdin AND stdout are a terminal, for pipelining
+pub fn is_terminal() -> bool {
+    std::io::stdin().is_terminal() && std::io::stdout().is_terminal()
+}
+
+/// The CLI's operating mode
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
+pub enum Mode {
+    Lex,
+    Fmt,
+    #[default]
+    Run,
+}
+
+impl FromStr for Mode {
+    type Err = &'static str;
+    fn from_str(s: &str) -> Result<Self, &'static str> {
+        Ok(match s {
+            "f" | "fmt" | "p" | "pretty" => Mode::Fmt,
+            "l" | "lex" | "tokenize" | "token" => Mode::Lex,
+            "r" | "run" => Mode::Run,
+            _ => Err("Recognized modes are: 'r' \"run\", 'f' \"fmt\", 'l' \"lex\"")?,
+        })
+    }
+}

compiler/cl-repl/src/bin/conlang.rs

@@ -0,0 +1,5 @@
+use cl_repl::{args, cli::run};
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    run(args::Args::args()?)
+}

compiler/cl-repl/src/cli.rs

@@ -0,0 +1,171 @@
+//! Implement's the command line interface
+use crate::{
+    args::{Args, Mode},
+    ctx::Context,
+    menu,
+    tools::print_token,
+};
+use cl_ast::File;
+use cl_interpret::{builtin::builtins, convalue::ConValue, env::Environment, interpret::Interpret};
+use cl_lexer::Lexer;
+use cl_parser::Parser;
+use std::{borrow::Cow, error::Error, path::Path};
+
+/// Run the command line interface
+pub fn run(args: Args) -> Result<(), Box<dyn Error>> {
+    let Args { file, include, mode, repl } = args;
+
+    let mut env = Environment::new();
+
+    env.add_builtins(&builtins! {
+        /// Lexes, parses, and evaluates an expression in the current env
+        fn eval(string) @env {
+            use cl_interpret::error::Error;
+            let string = match string {
+                ConValue::Str(string) => string.to_ref(),
+                ConValue::String(string) => string.as_str(),
+                ConValue::Ref(v) => {
+                    let string = env.get_id(*v).cloned().unwrap_or_default();
+                    return eval(env, &[string])
+                }
+                _ => Err(Error::TypeError())?
+            };
+            match Parser::new("eval", Lexer::new(string)).parse::<cl_ast::Stmt>() {
+                Err(e) => Ok(ConValue::Str(format!("{e}").into())),
+                Ok(v) => v.interpret(env),
+            }
+        }
+
+        /// Executes a file
+        fn import(path) @env {
+            use cl_interpret::error::Error;
+            match path {
+                ConValue::Str(path) => load_file(env, &**path).or(Ok(ConValue::Empty)),
+                ConValue::String(path) => load_file(env, &**path).or(Ok(ConValue::Empty)),
+                _ => Err(Error::TypeError())
+            }
+        }
+
+        fn putchar(ConValue::Char(c)) {
+            print!("{c}");
+            Ok(ConValue::Empty)
+        }
+
+        /// Gets a line of input from stdin
+        fn get_line(prompt) {
+            use cl_interpret::error::Error;
+            let prompt = match prompt {
+                ConValue::Str(prompt) => prompt.to_ref(),
+                ConValue::String(prompt) => prompt.as_str(),
+                _ => Err(Error::TypeError())?,
+            };
+            match repline::Repline::new("", prompt, "").read() {
+                Ok(line) => Ok(ConValue::String(line)),
+                Err(repline::Error::CtrlD(line)) => Ok(ConValue::String(line)),
+                Err(repline::Error::CtrlC(_)) => Err(cl_interpret::error::Error::Break(ConValue::Empty)),
+                Err(e) => Ok(ConValue::Str(e.to_string().into())),
+            }
+        }
+    });
+
+    for path in include {
+        load_file(&mut env, path)?;
+    }
+
+    if repl {
+        if let Some(file) = file
+            && let Err(e) = load_file(&mut env, file)
+        {
+            eprintln!("{e}")
+        }
+        let mut ctx = Context::with_env(env);
+        menu::main_menu(mode, &mut ctx)?;
+    } else {
+        let path = format_path_for_display(file.as_deref());
+        let code = match &file {
+            Some(file) => std::fs::read_to_string(file)?,
+            None => std::io::read_to_string(std::io::stdin())?,
+        };
+
+        match mode {
+            Mode::Lex => lex_code(&path, &code),
+            Mode::Fmt => fmt_code(&path, &code),
+            Mode::Run => run_code(&path, &code, &mut env),
+        }?;
+    }
+    Ok(())
+}
+
+fn format_path_for_display(path: Option<&Path>) -> Cow<'_, str> {
+    match path {
+        Some(file) => file
+            .to_str()
+            .map(Cow::Borrowed)
+            .unwrap_or_else(|| Cow::Owned(file.display().to_string())),
+        None => Cow::Borrowed(""),
+    }
+}
+
+fn load_file(env: &mut Environment, path: impl AsRef<Path>) -> Result<ConValue, Box<dyn Error>> {
+    let path = path.as_ref();
+    let inliner = cl_parser::inliner::ModuleInliner::new(path.with_extension(""));
+    let file = std::fs::read_to_string(path)?;
+    let code = Parser::new(path.display().to_string(), Lexer::new(&file)).parse()?;
+    let code = match inliner.inline(code) {
+        Ok(a) => a,
+        Err((code, io_errs, parse_errs)) => {
+            for (file, err) in io_errs {
+                eprintln!("{}:{err}", file.display());
+            }
+            for (file, err) in parse_errs {
+                eprintln!("{}:{err}", file.display());
+            }
+            code
+        }
+    };
+    use cl_ast::WeightOf;
+    eprintln!("File {} weighs {} units", code.name, code.weight_of());
+
+    match env.eval(&code) {
+        Ok(v) => Ok(v),
+        Err(e) => {
+            eprintln!("{e}");
+            Ok(ConValue::Empty)
+        }
+    }
+}
+
+fn lex_code(path: &str, code: &str) -> Result<(), Box<dyn Error>> {
+    for token in Lexer::new(code) {
+        if !path.is_empty() {
+            print!("{}:", path);
+        }
+        match token {
+            Ok(token) => print_token(&token),
+            Err(e) => println!("{e}"),
+        }
+    }
+    Ok(())
+}
+
+fn fmt_code(path: &str, code: &str) -> Result<(), Box<dyn Error>> {
+    let code = Parser::new(path, Lexer::new(code)).parse::<File>()?;
+    println!("{code}");
+    Ok(())
+}
+
+fn run_code(path: &str, code: &str, env: &mut Environment) -> Result<(), Box<dyn Error>> {
+    let code = Parser::new(path, Lexer::new(code)).parse::<File>()?;
+    match code.interpret(env)? {
+        ConValue::Empty => {}
+        ret => println!("{ret}"),
+    }
+    if env.get("main".into()).is_ok() {
+        match env.call("main".into(), &[]) {
+            Ok(ConValue::Empty) => {}
+            Ok(ret) => println!("{ret}"),
+            Err(e) => println!("Error: {e}"),
+        }
+    }
+    Ok(())
+}

compiler/cl-repl/src/ctx.rs

@@ -0,0 +1,24 @@
+use cl_interpret::{convalue::ConValue, env::Environment, error::IResult, interpret::Interpret};
+
+#[derive(Clone, Debug)]
+pub struct Context {
+    pub env: Environment,
+}
+
+impl Context {
+    pub fn new() -> Self {
+        Self { env: Environment::new() }
+    }
+    pub fn with_env(env: Environment) -> Self {
+        Self { env }
+    }
+    pub fn run(&mut self, code: &impl Interpret) -> IResult<ConValue> {
+        code.interpret(&mut self.env)
+    }
+}
+
+impl Default for Context {
+    fn default() -> Self {
+        Self::new()
+    }
+}

compiler/cl-repl/src/lib.rs

@@ -0,0 +1,11 @@
+//! The Conlang REPL, based on [repline]
+//!
+//! Uses [argwerk] for argument parsing.
+#![warn(clippy::all)]
+
+pub mod ansi;
+pub mod args;
+pub mod cli;
+pub mod ctx;
+pub mod menu;
+pub mod tools;

compiler/cl-repl/src/menu.rs

@@ -0,0 +1,126 @@
+use std::error::Error;
+
+use crate::{ansi, args::Mode, ctx};
+use cl_ast::Stmt;
+use cl_interpret::convalue::ConValue;
+use cl_lexer::Lexer;
+use cl_parser::Parser;
+use repline::{Error as RlError, error::ReplResult, prebaked::*};
+
+pub fn clear() {
+    print!("{}", ansi::CLEAR_ALL);
+    banner()
+}
+
+pub fn banner() {
+    println!("--- conlang v{} 💪🦈 ---", env!("CARGO_PKG_VERSION"))
+}
+
+type ReplCallback = fn(&mut ctx::Context, &str) -> Result<Response, Box<dyn Error>>;
+type ReplMode = (&'static str, &'static str, &'static str, ReplCallback);
+
+#[rustfmt::skip]
+const MODES: &[ReplMode] = &[
+    (ansi::CYAN,            ".>", " >", mode_run),
+    (ansi::BRIGHT_BLUE,     "l>", " >", mode_lex),
+    (ansi::BRIGHT_MAGENTA,  "f>", " >", mode_fmt),
+];
+
+const fn get_mode(mode: Mode) -> ReplMode {
+    match mode {
+        Mode::Lex => MODES[1],
+        Mode::Fmt => MODES[2],
+        Mode::Run => MODES[0],
+    }
+}
+
+/// Presents a selection interface to the user
+pub fn main_menu(mode: Mode, ctx: &mut ctx::Context) -> ReplResult<()> {
+    let mut mode = get_mode(mode);
+    banner();
+
+    let mut rl = repline::Repline::new(mode.0, mode.1, mode.2);
+    loop {
+        rl.set_prompt(mode.0, mode.1, mode.2);
+
+        let line = match rl.read() {
+            Err(RlError::CtrlC(_)) => return Ok(()),
+            Err(RlError::CtrlD(line)) => {
+                rl.deny();
+                line
+            }
+            Ok(line) => line,
+            Err(e) => Err(e)?,
+        };
+        print!("\x1b[G\x1b[J");
+        match line.trim() {
+            "" => continue,
+            "clear" => clear(),
+            "mode run" => mode = get_mode(Mode::Run),
+            "mode lex" => mode = get_mode(Mode::Lex),
+            "mode fmt" => mode = get_mode(Mode::Fmt),
+            "quit" => return Ok(()),
+            "help" => println!(
+                "Valid commands
+    help     : Print this list
+    clear    : Clear the screen
+    quit     : Exit the program
+    mode lex : Lex the input
+    mode fmt : Format the input
+    mode run : Evaluate some expressions"
+            ),
+            _ => match mode.3(ctx, &line) {
+                Ok(Response::Accept) => {
+                    rl.accept();
+                    continue;
+                }
+                Ok(Response::Deny) => {}
+                Ok(Response::Break) => return Ok(()),
+                Ok(Response::Continue) => continue,
+                Err(e) => rl.print_inline(format_args!("\t\x1b[91m{e}\x1b[0m"))?,
+            },
+        }
+        rl.deny();
+    }
+}
+
+pub fn mode_run(ctx: &mut ctx::Context, line: &str) -> Result<Response, Box<dyn Error>> {
+    use cl_ast::ast_visitor::Fold;
+    use cl_parser::inliner::ModuleInliner;
+
+    if line.trim().is_empty() {
+        return Ok(Response::Deny);
+    }
+    let code = Parser::new("", Lexer::new(line)).parse::<Stmt>()?;
+    let code = ModuleInliner::new(".").fold_stmt(code);
+
+    print!("{}", ansi::OUTPUT);
+    match ctx.run(&code) {
+        Ok(ConValue::Empty) => print!("{}", ansi::RESET),
+        Ok(v) => println!("{}{v}", ansi::RESET),
+        Err(e) => println!("{}! > {e}{}", ansi::RED, ansi::RESET),
+    }
+    Ok(Response::Accept)
+}
+
+pub fn mode_lex(_ctx: &mut ctx::Context, line: &str) -> Result<Response, Box<dyn Error>> {
+    for token in Lexer::new(line) {
+        match token {
+            Ok(token) => crate::tools::print_token(&token),
+            Err(e) => eprintln!("! > {}{e}{}", ansi::RED, ansi::RESET),
+        }
+    }
+
+    Ok(Response::Accept)
+}
+
+pub fn mode_fmt(_ctx: &mut ctx::Context, line: &str) -> Result<Response, Box<dyn Error>> {
+    let mut p = Parser::new("", Lexer::new(line));
+
+    match p.parse::<Stmt>() {
+        Ok(code) => println!("{}{code}{}", ansi::OUTPUT, ansi::RESET),
+        Err(e) => Err(e)?,
+    }
+
+    Ok(Response::Accept)
+}

compiler/cl-repl/src/tools.rs

@@ -0,0 +1,11 @@
+use cl_token::Token;
+/// Prints a token in the particular way [cl-repl](crate) does
+pub fn print_token(t: &Token) {
+    println!(
+        "{:02}:{:02}: {:#19} │{}│",
+        t.line(),
+        t.col(),
+        t.ty(),
+        t.data(),
+    )
+}

compiler/cl-structures/Cargo.toml

@@ -8,3 +8,4 @@ license.workspace = true
 publish.workspace = true
 
 [dependencies]
+cl-arena = { version = "0", registry = "soft-fish" }

compiler/cl-structures/src/index_map.rs

@@ -0,0 +1,219 @@
+//! Trivially-copyable, easily comparable typed [indices](MapIndex),
+//! and an [IndexMap] to contain them.
+//!
+//! # Examples
+//!
+//! ```rust
+//! # use cl_structures::index_map::*;
+//! // first, create a new MapIndex type (this ensures type safety)
+//! make_index! {
+//!     Number
+//! }
+//!
+//! // then, create a map with that type
+//! let mut numbers: IndexMap<Number, i32> = IndexMap::new();
+//! let first = numbers.insert(1);
+//! let second = numbers.insert(2);
+//! let third = numbers.insert(3);
+//!
+//! // You can access elements immutably with `get`
+//! assert_eq!(Some(&3), numbers.get(third));
+//! assert_eq!(Some(&2), numbers.get(second));
+//! // or by indexing
+//! assert_eq!(1, numbers[first]);
+//!
+//! // Or mutably
+//! *numbers.get_mut(first).unwrap() = 100000;
+//!
+//! assert_eq!(Some(&100000), numbers.get(first));
+//! ```
+
+/// Creates newtype indices over [`usize`] for use as [IndexMap] keys.
+///
+/// Generated key types implement [Clone], [Copy],
+/// [Debug](core::fmt::Debug), [PartialEq], [Eq], [PartialOrd], [Ord], [Hash](core::hash::Hash),
+/// and [MapIndex].
+#[macro_export]
+macro_rules! make_index {($($(#[$meta:meta])* $name:ident),*$(,)?) => {$(
+    $(#[$meta])*
+    #[repr(transparent)]
+    #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+    pub struct $name(usize);
+
+    impl $crate::index_map::MapIndex for $name {
+        #[doc = concat!("Constructs a [`", stringify!($name), "`] from a [`usize`] without checking bounds.\n")]
+        /// The provided value should be within the bounds of its associated container
+        #[inline]
+        fn from_usize(value: usize) -> Self {
+            Self(value)
+        }
+        #[inline]
+        fn get(&self) -> usize {
+            self.0
+        }
+    }
+
+    impl From< $name > for usize {
+        fn from(value: $name) -> Self {
+            value.0
+        }
+    }
+)*}}
+
+use self::iter::MapIndexIter;
+use std::{
+    ops::{Index, IndexMut},
+    slice::GetDisjointMutError,
+};
+
+pub use make_index;
+
+/// An index into a [IndexMap]. For full type-safety,
+/// there should be a unique [MapIndex] for each [IndexMap].
+pub trait MapIndex: std::fmt::Debug {
+    /// Constructs an [`MapIndex`] from a [`usize`] without checking bounds.
+    ///
+    /// The provided value should be within the bounds of its associated container.
+    fn from_usize(value: usize) -> Self;
+    /// Gets the index of the [`MapIndex`] by value
+    fn get(&self) -> usize;
+}
+
+/// It's an array. Lmao.
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct IndexMap<K: MapIndex, V> {
+    map: Vec<V>,
+    id_type: std::marker::PhantomData<K>,
+}
+
+impl<V, K: MapIndex> IndexMap<K, V> {
+    /// Constructs an empty IndexMap.
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Gets a reference to the value in slot `index`.
+    pub fn get(&self, index: K) -> Option<&V> {
+        self.map.get(index.get())
+    }
+
+    /// Gets a mutable reference to the value in slot `index`.
+    pub fn get_mut(&mut self, index: K) -> Option<&mut V> {
+        self.map.get_mut(index.get())
+    }
+
+    /// Returns mutable references to many indices at once.
+    ///
+    /// Returns an error if any index is out of bounds, or if the same index was passed twice.
+    pub fn get_disjoint_mut<const N: usize>(
+        &mut self,
+        indices: [K; N],
+    ) -> Result<[&mut V; N], GetDisjointMutError> {
+        self.map.get_disjoint_mut(indices.map(|id| id.get()))
+    }
+
+    /// Returns an iterator over the IndexMap.
+    pub fn values(&self) -> impl Iterator<Item = &V> {
+        self.map.iter()
+    }
+
+    /// Returns an iterator that allows modifying each value.
+    pub fn values_mut(&mut self) -> impl Iterator<Item = &mut V> {
+        self.map.iter_mut()
+    }
+
+    /// Returns an iterator over all keys in the IndexMap.
+    pub fn keys(&self) -> iter::MapIndexIter<K> {
+        // Safety: IndexMap currently has map.len() entries, and data cannot be removed
+        MapIndexIter::new(0..self.map.len())
+    }
+
+    /// Constructs an [ID](MapIndex) from a [usize], if it's within bounds
+    #[doc(hidden)]
+    pub fn try_key_from(&self, value: usize) -> Option<K> {
+        (value < self.map.len()).then(|| K::from_usize(value))
+    }
+
+    /// Inserts a new item into the IndexMap, returning the key associated with it.
+    pub fn insert(&mut self, value: V) -> K {
+        let id = self.map.len();
+        self.map.push(value);
+
+        // Safety: value was pushed to `self.map[id]`
+        K::from_usize(id)
+    }
+
+    /// Replaces a value in the IndexMap, returning the old value.
+    pub fn replace(&mut self, key: K, value: V) -> V {
+        std::mem::replace(&mut self[key], value)
+    }
+}
+
+impl<K: MapIndex, V> Default for IndexMap<K, V> {
+    fn default() -> Self {
+        Self { map: vec![], id_type: std::marker::PhantomData }
+    }
+}
+
+impl<K: MapIndex, V> Index<K> for IndexMap<K, V> {
+    type Output = V;
+
+    fn index(&self, index: K) -> &Self::Output {
+        match self.map.get(index.get()) {
+            None => panic!("Index {:?} out of bounds in IndexMap!", index),
+            Some(value) => value,
+        }
+    }
+}
+
+impl<K: MapIndex, V> IndexMut<K> for IndexMap<K, V> {
+    fn index_mut(&mut self, index: K) -> &mut Self::Output {
+        match self.map.get_mut(index.get()) {
+            None => panic!("Index {:?} out of bounds in IndexMap!", index),
+            Some(value) => value,
+        }
+    }
+}
+
+mod iter {
+    //! Iterators for [IndexMap](super::IndexMap)
+    use super::MapIndex;
+    use std::{marker::PhantomData, ops::Range};
+
+    /// Iterates over the keys of an [IndexMap](super::IndexMap), independently of the map.
+    ///
+    /// This is guaranteed to never overrun the length of the map, but is *NOT* guaranteed
+    /// to iterate over all elements of the map if the map is extended during iteration.
+    #[derive(Clone, Debug, PartialEq, Eq, Hash)]
+    pub struct MapIndexIter<K: MapIndex> {
+        range: Range<usize>,
+        _id: PhantomData<K>,
+    }
+
+    impl<K: MapIndex> MapIndexIter<K> {
+        /// Creates a new [MapIndexIter] producing the given [MapIndex]
+        pub(super) fn new(range: Range<usize>) -> Self {
+            Self { range, _id: PhantomData }
+        }
+    }
+
+    impl<ID: MapIndex> Iterator for MapIndexIter<ID> {
+        type Item = ID;
+
+        fn next(&mut self) -> Option<Self::Item> {
+            Some(ID::from_usize(self.range.next()?))
+        }
+        fn size_hint(&self) -> (usize, Option<usize>) {
+            self.range.size_hint()
+        }
+    }
+
+    impl<ID: MapIndex> DoubleEndedIterator for MapIndexIter<ID> {
+        fn next_back(&mut self) -> Option<Self::Item> {
+            // Safety: see above
+            Some(ID::from_usize(self.range.next_back()?))
+        }
+    }
+
+    impl<ID: MapIndex> ExactSizeIterator for MapIndexIter<ID> {}
+}

compiler/cl-structures/src/intern.rs

@@ -0,0 +1,319 @@
+//! Interners for [strings](string_interner) and arbitrary [types](typed_interner).
+//!
+//! An object is [Interned][1] if it is allocated within one of the interners
+//! in this module. [Interned][1] values have referential equality semantics, and
+//! [Deref](std::ops::Deref) to the value within their respective intern pool.
+//!
+//! This means, of course, that the same value interned in two different pools will be
+//! considered *not equal* by [Eq] and [Hash](std::hash::Hash).
+//!
+//! [1]: interned::Interned
+
+pub mod interned {
+    //! An [Interned] reference asserts its wrapped value has referential equality.
+    use super::string_interner::StringInterner;
+    use std::{
+        fmt::{Debug, Display},
+        hash::Hash,
+        ops::Deref,
+    };
+
+    /// An [Interned] value is one that is *referentially comparable*.
+    /// That is, the interned value is unique in memory, simplifying
+    /// its equality and hashing implementation.
+    ///
+    /// Comparing [Interned] values via [PartialOrd] or [Ord] will still
+    /// dereference to the wrapped pointers, and as such, may produce
+    /// results inconsistent with [PartialEq] or [Eq].
+    #[repr(transparent)]
+    pub struct Interned<'a, T: ?Sized> {
+        value: &'a T,
+    }
+
+    impl<'a, T: ?Sized> Interned<'a, T> {
+        /// Gets the internal value as a pointer
+        pub fn as_ptr(interned: &Self) -> *const T {
+            interned.value
+        }
+
+        /// Gets the internal value as a reference with the interner's lifetime
+        pub fn to_ref(&self) -> &'a T {
+            self.value
+        }
+    }
+
+    impl<T: ?Sized + Debug> Debug for Interned<'_, T> {
+        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+            write!(f, "~")?;
+            self.value.fmt(f)
+        }
+    }
+    impl<'a, T: ?Sized> Interned<'a, T> {
+        pub(super) fn new(value: &'a T) -> Self {
+            Self { value }
+        }
+    }
+    impl<T: ?Sized> Deref for Interned<'_, T> {
+        type Target = T;
+        fn deref(&self) -> &Self::Target {
+            self.value
+        }
+    }
+    impl<T: ?Sized> Copy for Interned<'_, T> {}
+    impl<T: ?Sized> Clone for Interned<'_, T> {
+        fn clone(&self) -> Self {
+            *self
+        }
+    }
+    // TODO: These implementations are subtly incorrect, as they do not line up with `eq`
+    // impl<'a, T: ?Sized + PartialOrd> PartialOrd for Interned<'a, T> {
+    //     fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+    //         match self == other {
+    //             true => Some(std::cmp::Ordering::Equal),
+    //             false => self.value.partial_cmp(other.value),
+    //         }
+    //     }
+    // }
+    // impl<'a, T: ?Sized + Ord> Ord for Interned<'a, T> {
+    //     fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+    //         match self == other {
+    //             true => std::cmp::Ordering::Equal,
+    //             false => self.value.cmp(other.value),
+    //         }
+    //     }
+    // }
+
+    impl<T: ?Sized> Eq for Interned<'_, T> {}
+    impl<T: ?Sized> PartialEq for Interned<'_, T> {
+        fn eq(&self, other: &Self) -> bool {
+            std::ptr::eq(self.value, other.value)
+        }
+    }
+    impl<T: ?Sized> Hash for Interned<'_, T> {
+        fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+            Self::as_ptr(self).hash(state)
+        }
+    }
+    impl<T: ?Sized + Display> Display for Interned<'_, T> {
+        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+            self.value.fmt(f)
+        }
+    }
+
+    impl<T: AsRef<str>> From<T> for Interned<'static, str> {
+        /// Types which implement [`AsRef<str>`] will be stored in the global [StringInterner]
+        fn from(value: T) -> Self {
+            from_str(value.as_ref())
+        }
+    }
+    fn from_str(value: &str) -> Interned<'static, str> {
+        let global_interner = StringInterner::global();
+        global_interner.get_or_insert(value)
+    }
+}
+
+pub mod string_interner {
+    //! A [StringInterner] hands out [Interned] copies of each unique string given to it.
+
+    use super::interned::Interned;
+    use cl_arena::dropless_arena::DroplessArena;
+    use std::{
+        collections::HashSet,
+        sync::{OnceLock, RwLock},
+    };
+
+    /// A string interner hands out [Interned] copies of each unique string given to it.
+    #[derive(Default)]
+    pub struct StringInterner<'a> {
+        arena: DroplessArena<'a>,
+        keys: RwLock<HashSet<&'a str>>,
+    }
+
+    impl StringInterner<'static> {
+        /// Gets a reference to a global string interner whose [Interned] strings are `'static`
+        pub fn global() -> &'static Self {
+            static GLOBAL_INTERNER: OnceLock<StringInterner<'static>> = OnceLock::new();
+
+            // SAFETY: The RwLock within the interner's `keys` protects the arena
+            // from being modified concurrently.
+            GLOBAL_INTERNER.get_or_init(|| StringInterner {
+                arena: DroplessArena::new(),
+                keys: Default::default(),
+            })
+        }
+    }
+
+    impl<'a> StringInterner<'a> {
+        /// Creates a new [StringInterner] backed by the provided [DroplessArena]
+        pub fn new(arena: DroplessArena<'a>) -> Self {
+            Self { arena, keys: RwLock::new(HashSet::new()) }
+        }
+
+        /// Returns an [Interned] copy of the given string,
+        /// allocating a new one if it doesn't already exist.
+        ///
+        /// # Blocks
+        /// This function blocks when the interner is held by another thread.
+        pub fn get_or_insert(&'a self, value: &str) -> Interned<'a, str> {
+            let Self { arena, keys } = self;
+
+            // Safety: Holding this write guard for the entire duration of this
+            // function enforces a safety invariant. See StringInterner::global.
+            let mut keys = keys.write().expect("should not be poisoned");
+
+            Interned::new(match keys.get(value) {
+                Some(value) => value,
+                None => {
+                    let value = match value {
+                        "" => "", // Arena will panic if passed an empty string
+                        _ => arena.alloc_str(value),
+                    };
+                    keys.insert(value);
+                    value
+                }
+            })
+        }
+        /// Gets a reference to the interned copy of the given value, if it exists
+        /// # Blocks
+        /// This function blocks when the interner is held by another thread.
+        pub fn get(&'a self, value: &str) -> Option<Interned<'a, str>> {
+            let keys = self.keys.read().expect("should not be poisoned");
+            keys.get(value).copied().map(Interned::new)
+        }
+    }
+
+    impl std::fmt::Debug for StringInterner<'_> {
+        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+            f.debug_struct("Interner")
+                .field("keys", &self.keys)
+                .finish()
+        }
+    }
+
+    impl std::fmt::Display for StringInterner<'_> {
+        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+            let Ok(keys) = self.keys.read() else {
+                return write!(f, "Could not lock StringInterner key map.");
+            };
+            let mut keys: Vec<_> = keys.iter().collect();
+            keys.sort();
+
+            writeln!(f, "Keys:")?;
+            for (idx, key) in keys.iter().enumerate() {
+                writeln!(f, "{idx}:\t\"{key}\"")?
+            }
+            writeln!(f, "Count: {}", keys.len())?;
+
+            Ok(())
+        }
+    }
+
+    // # Safety:
+    // This is fine because StringInterner::get_or_insert(v) holds a RwLock
+    // for its entire duration, and doesn't touch the non-(Send+Sync) arena
+    // unless the lock is held by a write guard.
+    unsafe impl Send for StringInterner<'_> {}
+    unsafe impl Sync for StringInterner<'_> {}
+
+    #[cfg(test)]
+    mod tests {
+        use super::StringInterner;
+
+        macro_rules! ptr_eq {
+        ($a: expr, $b: expr $(, $($t:tt)*)?) => {
+            assert_eq!(std::ptr::addr_of!($a), std::ptr::addr_of!($b) $(, $($t)*)?)
+        };
+    }
+        macro_rules! ptr_ne {
+        ($a: expr, $b: expr $(, $($t:tt)*)?) => {
+            assert_ne!(std::ptr::addr_of!($a), std::ptr::addr_of!($b) $(, $($t)*)?)
+        };
+    }
+
+        #[test]
+        fn empties_is_unique() {
+            let interner = StringInterner::global();
+            let empty = interner.get_or_insert("");
+            let empty2 = interner.get_or_insert("");
+            ptr_eq!(*empty, *empty2);
+        }
+        #[test]
+        fn non_empty_is_unique() {
+            let interner = StringInterner::global();
+            let nonempty1 = interner.get_or_insert("not empty!");
+            let nonempty2 = interner.get_or_insert("not empty!");
+            let different = interner.get_or_insert("different!");
+            ptr_eq!(*nonempty1, *nonempty2);
+            ptr_ne!(*nonempty1, *different);
+        }
+    }
+}
+
+pub mod typed_interner {
+    //! A [TypedInterner] hands out [Interned] references for arbitrary types.
+    //!
+    //! Note: It is a *logic error* to modify the returned reference via interior mutability
+    //! in a way that changes the values produced by [Eq] and [Hash].
+    //!
+    //! See the standard library [HashSet] for more details.
+    use super::interned::Interned;
+    use cl_arena::typed_arena::TypedArena;
+    use std::{collections::HashSet, hash::Hash, sync::RwLock};
+
+    /// A [TypedInterner] hands out [Interned] references for arbitrary types.
+    ///
+    /// See the [module-level documentation](self) for more information.
+    pub struct TypedInterner<'a, T: Eq + Hash> {
+        arena: TypedArena<'a, T>,
+        keys: RwLock<HashSet<&'a T>>,
+    }
+
+    impl<'a, T: Eq + Hash> Default for TypedInterner<'a, T> {
+        fn default() -> Self {
+            Self { arena: Default::default(), keys: Default::default() }
+        }
+    }
+
+    impl<'a, T: Eq + Hash> TypedInterner<'a, T> {
+        /// Creates a new [TypedInterner] backed by the provided [TypedArena]
+        pub fn new(arena: TypedArena<'a, T>) -> Self {
+            Self { arena, keys: RwLock::new(HashSet::new()) }
+        }
+
+        /// Converts the given value into an [Interned] value.
+        ///
+        /// # Blocks
+        /// This function blocks when the interner is held by another thread.
+        pub fn get_or_insert(&'a self, value: T) -> Interned<'a, T> {
+            let Self { arena, keys } = self;
+
+            // Safety: Locking the keyset for the entire duration of this function
+            // enforces a safety invariant when the interner is stored in a global.
+            let mut keys = keys.write().expect("should not be poisoned");
+
+            Interned::new(match keys.get(&value) {
+                Some(value) => value,
+                None => {
+                    let value = arena.alloc(value);
+                    keys.insert(value);
+                    value
+                }
+            })
+        }
+        /// Returns the [Interned] copy of the given value, if one already exists
+        ///
+        /// # Blocks
+        /// This function blocks when the interner is being written to by another thread.
+        pub fn get(&self, value: &T) -> Option<Interned<'a, T>> {
+            let keys = self.keys.read().expect("should not be poisoned");
+            keys.get(value).copied().map(Interned::new)
+        }
+    }
+
+    /// # Safety
+    /// This should be safe because references yielded by
+    /// [get_or_insert](TypedInterner::get_or_insert) are unique, and the function uses
+    /// the [RwLock] around the [HashSet] to ensure mutual exclusion
+    unsafe impl<'a, T: Eq + Hash + Send> Send for TypedInterner<'a, T> where &'a T: Send {}
+    unsafe impl<T: Eq + Hash + Send + Sync> Sync for TypedInterner<'_, T> {}
+}

compiler/cl-structures/src/lib.rs

@@ -0,0 +1,24 @@
+//! # Universally useful structures
+//! - [Span](struct@span::Span): Stores a start and end [Loc](struct@span::Loc)
+//! - [Loc](struct@span::Loc): Stores the index in a stream
+//! - [TypedInterner][ti] & [StringInterner][si]: Provies stable, unique allocations
+//! - [Stack](stack::Stack): Contiguous collections with constant capacity
+//! - [IndexMap][im]: A map from [map indices][mi] to values
+//!
+//! [ti]: intern::typed_interner::TypedInterner
+//! [si]: intern::string_interner::StringInterner
+//! [im]: index_map::IndexMap
+//! [mi]: index_map::MapIndex
+#![warn(clippy::all)]
+#![feature(dropck_eyepatch, decl_macro)]
+#![deny(unsafe_op_in_unsafe_fn)]
+
+pub mod intern;
+
+pub mod span;
+
+pub mod tree;
+
+pub mod stack;
+
+pub mod index_map;

compiler/cl-structures/src/span.rs

@@ -8,24 +8,33 @@ pub struct Span {
     pub head: Loc,
     pub tail: Loc,
 }
-pub fn Span(head: Loc, tail: Loc) -> Span {
+pub const fn Span(head: Loc, tail: Loc) -> Span {
     Span { head, tail }
 }
 
+impl Span {
+    pub const fn dummy() -> Self {
+        Span { head: Loc::dummy(), tail: Loc::dummy() }
+    }
+}
+
 /// Stores a read-only (line, column) location in a token stream
 #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct Loc {
     line: u32,
     col: u32,
 }
-pub fn Loc(line: u32, col: u32) -> Loc {
+pub const fn Loc(line: u32, col: u32) -> Loc {
     Loc { line, col }
 }
 impl Loc {
-    pub fn line(self) -> u32 {
+    pub const fn dummy() -> Self {
+        Loc { line: 0, col: 0 }
+    }
+    pub const fn line(self) -> u32 {
         self.line
     }
-    pub fn col(self) -> u32 {
+    pub const fn col(self) -> u32 {
         self.col
     }
 }
@@ -33,6 +42,6 @@ impl Loc {
 impl std::fmt::Display for Loc {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         let Loc { line, col } = self;
-        write!(f, "{line}:{col}:")
+        write!(f, "{line}:{col}")
     }
 }

compiler/cl-structures/src/stack.rs

@@ -93,8 +93,8 @@ use std::{
 /// assert_eq!(Some(&10), v.last());
 /// ```
 pub macro stack {
-    ($count:literal) => {
-        Stack::<_, $count>::new()
+    ($capacity:literal) => {
+        Stack::<_, $capacity>::new()
     },
     ($value:expr ; $count:literal) => {{
         let mut stack: Stack<_, $count> = Stack::new();
@@ -103,6 +103,13 @@ pub macro stack {
         }
         stack
     }},
+    ($value:expr ; $count:literal ; $capacity:literal) => {{
+        let mut stack: Stack<_, $capacity> = Stack::new();
+        for _ in 0..$count {
+            stack.push($value)
+        }
+        stack
+    }},
     ($($values:expr),* $(,)?) => {
         Stack::from([$($values),*])
     }
@@ -142,20 +149,14 @@ impl<T, const N: usize> Deref for Stack<T, N> {
 
     #[inline]
     fn deref(&self) -> &Self::Target {
-        // Safety:
-        // - We have ensured all elements from 0 to len have been initialized
-        // - self.elem[0] came from a reference, and so is aligned to T
-        // unsafe { &*(&self.buf[0..self.len] as *const [_] as *const [T]) }
-        unsafe { slice::from_raw_parts(self.buf.as_ptr().cast(), self.len) }
+        self.as_slice()
     }
 }
 
 impl<T, const N: usize> DerefMut for Stack<T, N> {
     #[inline]
     fn deref_mut(&mut self) -> &mut Self::Target {
-        // Safety:
-        // - See Deref
-        unsafe { slice::from_raw_parts_mut(self.buf.as_mut_ptr().cast(), self.len) }
+        self.as_mut_slice()
     }
 }
 
@@ -163,8 +164,10 @@ impl<T, const N: usize> DerefMut for Stack<T, N> {
 unsafe impl<#[may_dangle] T, const N: usize> Drop for Stack<T, N> {
     #[inline]
     fn drop(&mut self) {
-        // Safety: We have ensured that all elements in the list are
-        unsafe { core::ptr::drop_in_place(self.as_mut_slice()) };
+        // Safety: Elements in [0..self.len] are initialized
+        if std::mem::needs_drop::<T>() {
+            unsafe { core::ptr::drop_in_place(self.as_mut_slice()) };
+        }
     }
 }
 
@@ -269,18 +272,24 @@ impl<T, const N: usize> Stack<T, N> {
     }
 
     /// Returns an unsafe mutable pointer to the stack's buffer
-    pub fn as_mut_ptr(&mut self) -> *mut T {
+    pub const fn as_mut_ptr(&mut self) -> *mut T {
         self.buf.as_mut_ptr().cast()
     }
 
     /// Extracts a slice containing the entire vector
-    pub fn as_slice(&self) -> &[T] {
-        self
+    pub const fn as_slice(&self) -> &[T] {
+        // Safety:
+        // - We have ensured all elements from 0 to len have been initialized
+        // - self.elem[0] came from a reference, and so is aligned to T
+        // unsafe { &*(&self.buf[0..self.len] as *const [_] as *const [T]) }
+        unsafe { slice::from_raw_parts(self.buf.as_ptr().cast(), self.len) }
     }
 
     /// Extracts a mutable slice containing the entire vector
-    pub fn as_mut_slice(&mut self) -> &mut [T] {
-        self
+    pub const fn as_mut_slice(&mut self) -> &mut [T] {
+        // Safety:
+        // - See Stack::as_slice
+        unsafe { slice::from_raw_parts_mut(self.buf.as_mut_ptr().cast(), self.len) }
     }
 
     /// Returns the total number of elements the stack can hold
@@ -353,7 +362,7 @@ impl<T, const N: usize> Stack<T, N> {
     /// v.push(3);
     /// assert_eq!(&[0, 1, 2, 3], v.as_slice());
     /// ```
-    pub fn push(&mut self, value: T) {
+    pub const fn push(&mut self, value: T) {
         if self.len >= N {
             panic!("Attempted to push into full stack")
         }
@@ -364,7 +373,7 @@ impl<T, const N: usize> Stack<T, N> {
     /// Push a new element onto the end of the stack
     ///
     /// Returns [`Err(value)`](Result::Err) if the new length would exceed capacity
-    pub fn try_push(&mut self, value: T) -> Result<(), T> {
+    pub const fn try_push(&mut self, value: T) -> Result<(), T> {
         if self.len >= N {
             return Err(value);
         }
@@ -379,8 +388,11 @@ impl<T, const N: usize> Stack<T, N> {
     ///
     /// len after push must not exceed capacity N
     #[inline]
-    unsafe fn push_unchecked(&mut self, value: T) {
-        unsafe { ptr::write(self.as_mut_ptr().add(self.len), value) }
+    const unsafe fn push_unchecked(&mut self, value: T) {
+        unsafe {
+            // self.buf.get_unchecked_mut(self.len).write(value); // TODO: This is non-const
+            ptr::write(self.as_mut_ptr().add(self.len), value)
+        }
         self.len += 1; // post inc
     }
 
@@ -400,13 +412,14 @@ impl<T, const N: usize> Stack<T, N> {
     /// assert_eq!(Some(0), v.pop());
     /// assert_eq!(None, v.pop());
     /// ```
-    pub fn pop(&mut self) -> Option<T> {
+    pub const fn pop(&mut self) -> Option<T> {
         if self.len == 0 {
             None
         } else {
             self.len -= 1;
             // Safety: MaybeUninit<T> implies ManuallyDrop<T>,
             // therefore should not get dropped twice
+            // Some(unsafe { self.buf.get_unchecked_mut(self.len).assume_init_read() })
             Some(unsafe { ptr::read(self.as_ptr().add(self.len).cast()) })
         }
     }
@@ -505,7 +518,7 @@ impl<T, const N: usize> Stack<T, N> {
     ///
     /// assert_eq!(Ok(()), v.try_insert(0, 0));
     /// ```
-    pub fn try_insert(&mut self, index: usize, data: T) -> Result<(), (T, InsertFailed<N>)> {
+    pub const fn try_insert(&mut self, index: usize, data: T) -> Result<(), (T, InsertFailed<N>)> {
         if index > self.len {
             return Err((data, InsertFailed::Bounds(index)));
         }
@@ -521,7 +534,7 @@ impl<T, const N: usize> Stack<T, N> {
     /// - index must be less than self.len
     /// - length after insertion must be <= N
     #[inline]
-    unsafe fn insert_unchecked(&mut self, index: usize, data: T) {
+    const unsafe fn insert_unchecked(&mut self, index: usize, data: T) {
         let base = self.as_mut_ptr();
 
         unsafe { ptr::copy(base.add(index), base.add(index + 1), self.len - index) }
@@ -545,7 +558,9 @@ impl<T, const N: usize> Stack<T, N> {
     /// ```
     pub fn clear(&mut self) {
         // Hopefully copy elision takes care of this lmao
-        drop(std::mem::take(self))
+        while !self.is_empty() {
+            drop(self.pop());
+        }
     }
 
     /// Returns the number of elements in the stack
@@ -555,7 +570,7 @@ impl<T, const N: usize> Stack<T, N> {
     ///
     /// assert_eq!(5, v.len());
     /// ```
-    pub fn len(&self) -> usize {
+    pub const fn len(&self) -> usize {
         self.len
     }
 
@@ -570,7 +585,7 @@ impl<T, const N: usize> Stack<T, N> {
     /// assert!(v.is_full());
     /// ```
     #[inline]
-    pub fn is_full(&self) -> bool {
+    pub const fn is_full(&self) -> bool {
         self.len >= N
     }
 
@@ -585,7 +600,7 @@ impl<T, const N: usize> Stack<T, N> {
     /// assert!(v.is_empty());
     /// ```
     #[inline]
-    pub fn is_empty(&self) -> bool {
+    pub const fn is_empty(&self) -> bool {
         self.len == 0
     }
 }
@@ -617,13 +632,13 @@ mod tests {
         assert_eq!(std::mem::size_of::<usize>(), std::mem::size_of_val(&v))
     }
     #[test]
-    #[cfg_attr(debug_assertions, ignore = "calls ().drop() usize::MAX times")]
     fn from_usize_max_zst_array() {
         let mut v = Stack::from([(); usize::MAX]);
         assert_eq!(v.len(), usize::MAX);
         v.pop();
         assert_eq!(v.len(), usize::MAX - 1);
     }
+
     #[test]
     fn new() {
         let v: Stack<(), 255> = Stack::new();
@@ -744,4 +759,19 @@ mod tests {
         ]);
         std::mem::drop(std::hint::black_box(v));
     }
+
+    #[test]
+    fn drop_zst() {
+        struct Droppable;
+        impl Drop for Droppable {
+            fn drop(&mut self) {
+                use std::sync::atomic::{AtomicU32, Ordering};
+                static V: AtomicU32 = AtomicU32::new(1);
+                eprintln!("{}", V.fetch_add(1, Ordering::Relaxed));
+            }
+        }
+
+        let v = Stack::from([const { Droppable }; 10]);
+        std::mem::drop(v);
+    }
 }

compiler/cl-token/src/lib.rs

@@ -10,4 +10,4 @@ pub mod token_type;
 
 pub use token::Token;
 pub use token_data::TokenData;
-pub use token_type::{Punct, TokenKind};
+pub use token_type::TokenKind;

compiler/cl-token/src/token_type.rs

@@ -13,38 +13,35 @@ pub enum TokenKind {
     /// A non-keyword identifier
     Identifier,
     // A keyword
-    Break,
-    Cl,
-    Const,
-    Continue,
-    Else,
-    Enum,
-    False,
-    For,
-    Fn,
-    If,
-    Impl,
-    In,
-    Let,
-    Mod,
-    Mut,
-    Pub,
-    Return,
-    SelfKw,
-    SelfTy,
-    Static,
-    Struct,
-    Super,
-    True,
-    Type,
-    While,
-    /// Delimiter or punctuation
-    Punct(Punct),
-}
-
-/// An operator character (delimiter, punctuation)
-#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
-pub enum Punct {
+    As,       // as
+    Break,    // "break"
+    Cl,       // "cl"
+    Const,    // "const"
+    Continue, // "continue"
+    Else,     // "else"
+    Enum,     // "enum"
+    False,    // "false"
+    Fn,       // "fn"
+    For,      // "for"
+    If,       // "if"
+    Impl,     // "impl"
+    In,       // "in"
+    Let,      // "let"
+    Loop,     // "loop"
+    Match,    // "match"
+    Mod,      // "mod"
+    Mut,      // "mut"
+    Pub,      // "pub"
+    Return,   // "return"
+    SelfTy,   // "Self"
+    Static,   // "static"
+    Struct,   // "struct"
+    Super,    // "super"
+    True,     // "true"
+    Type,     // "type"
+    Use,      // "use"
+    While,    // "while"
+    // Delimiter or punctuation
     LCurly,     // {
     RCurly,     // }
     LBrack,     // [
@@ -109,6 +106,7 @@ impl Display for TokenKind {
             TokenKind::Literal => "literal".fmt(f),
             TokenKind::Identifier => "identifier".fmt(f),
 
+            TokenKind::As => "as".fmt(f),
             TokenKind::Break => "break".fmt(f),
             TokenKind::Cl => "cl".fmt(f),
             TokenKind::Const => "const".fmt(f),
@@ -116,26 +114,81 @@ impl Display for TokenKind {
             TokenKind::Else => "else".fmt(f),
             TokenKind::Enum => "enum".fmt(f),
             TokenKind::False => "false".fmt(f),
-            TokenKind::For => "for".fmt(f),
             TokenKind::Fn => "fn".fmt(f),
+            TokenKind::For => "for".fmt(f),
             TokenKind::If => "if".fmt(f),
             TokenKind::Impl => "impl".fmt(f),
             TokenKind::In => "in".fmt(f),
             TokenKind::Let => "let".fmt(f),
+            TokenKind::Loop => "loop".fmt(f),
+            TokenKind::Match => "match".fmt(f),
             TokenKind::Mod => "mod".fmt(f),
             TokenKind::Mut => "mut".fmt(f),
             TokenKind::Pub => "pub".fmt(f),
             TokenKind::Return => "return".fmt(f),
-            TokenKind::SelfKw => "self".fmt(f),
             TokenKind::SelfTy => "Self".fmt(f),
             TokenKind::Static => "static".fmt(f),
             TokenKind::Struct => "struct".fmt(f),
             TokenKind::Super => "super".fmt(f),
             TokenKind::True => "true".fmt(f),
             TokenKind::Type => "type".fmt(f),
+            TokenKind::Use => "use".fmt(f),
             TokenKind::While => "while".fmt(f),
 
-            TokenKind::Punct(op) => op.fmt(f),
+            TokenKind::LCurly => "{".fmt(f),
+            TokenKind::RCurly => "}".fmt(f),
+            TokenKind::LBrack => "[".fmt(f),
+            TokenKind::RBrack => "]".fmt(f),
+            TokenKind::LParen => "(".fmt(f),
+            TokenKind::RParen => ")".fmt(f),
+            TokenKind::Amp => "&".fmt(f),
+            TokenKind::AmpAmp => "&&".fmt(f),
+            TokenKind::AmpEq => "&=".fmt(f),
+            TokenKind::Arrow => "->".fmt(f),
+            TokenKind::At => "@".fmt(f),
+            TokenKind::Backslash => "\\".fmt(f),
+            TokenKind::Bang => "!".fmt(f),
+            TokenKind::BangBang => "!!".fmt(f),
+            TokenKind::BangEq => "!=".fmt(f),
+            TokenKind::Bar => "|".fmt(f),
+            TokenKind::BarBar => "||".fmt(f),
+            TokenKind::BarEq => "|=".fmt(f),
+            TokenKind::Colon => ":".fmt(f),
+            TokenKind::ColonColon => "::".fmt(f),
+            TokenKind::Comma => ",".fmt(f),
+            TokenKind::Dot => ".".fmt(f),
+            TokenKind::DotDot => "..".fmt(f),
+            TokenKind::DotDotEq => "..=".fmt(f),
+            TokenKind::Eq => "=".fmt(f),
+            TokenKind::EqEq => "==".fmt(f),
+            TokenKind::FatArrow => "=>".fmt(f),
+            TokenKind::Grave => "`".fmt(f),
+            TokenKind::Gt => ">".fmt(f),
+            TokenKind::GtEq => ">=".fmt(f),
+            TokenKind::GtGt => ">>".fmt(f),
+            TokenKind::GtGtEq => ">>=".fmt(f),
+            TokenKind::Hash => "#".fmt(f),
+            TokenKind::HashBang => "#!".fmt(f),
+            TokenKind::Lt => "<".fmt(f),
+            TokenKind::LtEq => "<=".fmt(f),
+            TokenKind::LtLt => "<<".fmt(f),
+            TokenKind::LtLtEq => "<<=".fmt(f),
+            TokenKind::Minus => "-".fmt(f),
+            TokenKind::MinusEq => "-=".fmt(f),
+            TokenKind::Plus => "+".fmt(f),
+            TokenKind::PlusEq => "+=".fmt(f),
+            TokenKind::Question => "?".fmt(f),
+            TokenKind::Rem => "%".fmt(f),
+            TokenKind::RemEq => "%=".fmt(f),
+            TokenKind::Semi => ";".fmt(f),
+            TokenKind::Slash => "/".fmt(f),
+            TokenKind::SlashEq => "/=".fmt(f),
+            TokenKind::Star => "*".fmt(f),
+            TokenKind::StarEq => "*=".fmt(f),
+            TokenKind::Tilde => "~".fmt(f),
+            TokenKind::Xor => "^".fmt(f),
+            TokenKind::XorEq => "^=".fmt(f),
+            TokenKind::XorXor => "^^".fmt(f),
         }
     }
 }
@@ -145,6 +198,7 @@ impl FromStr for TokenKind {
     /// Parses a string s to return a Keyword
     fn from_str(s: &str) -> Result<Self, Self::Err> {
         Ok(match s {
+            "as" => Self::As,
             "break" => Self::Break,
             "cl" => Self::Cl,
             "const" => Self::Const,
@@ -152,86 +206,27 @@ impl FromStr for TokenKind {
             "else" => Self::Else,
             "enum" => Self::Enum,
             "false" => Self::False,
-            "for" => Self::For,
             "fn" => Self::Fn,
+            "for" => Self::For,
             "if" => Self::If,
             "impl" => Self::Impl,
             "in" => Self::In,
             "let" => Self::Let,
+            "loop" => Self::Loop,
+            "match" => Self::Match,
             "mod" => Self::Mod,
             "mut" => Self::Mut,
             "pub" => Self::Pub,
             "return" => Self::Return,
-            "self" => Self::SelfKw,
             "Self" => Self::SelfTy,
             "static" => Self::Static,
             "struct" => Self::Struct,
             "super" => Self::Super,
             "true" => Self::True,
             "type" => Self::Type,
+            "use" => Self::Use,
             "while" => Self::While,
             _ => Err(())?,
         })
     }
 }
-
-impl Display for Punct {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match self {
-            Punct::LCurly => "{".fmt(f),
-            Punct::RCurly => "}".fmt(f),
-            Punct::LBrack => "[".fmt(f),
-            Punct::RBrack => "]".fmt(f),
-            Punct::LParen => "(".fmt(f),
-            Punct::RParen => ")".fmt(f),
-            Punct::Amp => "&".fmt(f),
-            Punct::AmpAmp => "&&".fmt(f),
-            Punct::AmpEq => "&=".fmt(f),
-            Punct::Arrow => "->".fmt(f),
-            Punct::At => "@".fmt(f),
-            Punct::Backslash => "\\".fmt(f),
-            Punct::Bang => "!".fmt(f),
-            Punct::BangBang => "!!".fmt(f),
-            Punct::BangEq => "!=".fmt(f),
-            Punct::Bar => "|".fmt(f),
-            Punct::BarBar => "||".fmt(f),
-            Punct::BarEq => "|=".fmt(f),
-            Punct::Colon => ":".fmt(f),
-            Punct::ColonColon => "::".fmt(f),
-            Punct::Comma => ",".fmt(f),
-            Punct::Dot => ".".fmt(f),
-            Punct::DotDot => "..".fmt(f),
-            Punct::DotDotEq => "..=".fmt(f),
-            Punct::Eq => "=".fmt(f),
-            Punct::EqEq => "==".fmt(f),
-            Punct::FatArrow => "=>".fmt(f),
-            Punct::Grave => "`".fmt(f),
-            Punct::Gt => ">".fmt(f),
-            Punct::GtEq => ">=".fmt(f),
-            Punct::GtGt => ">>".fmt(f),
-            Punct::GtGtEq => ">>=".fmt(f),
-            Punct::Hash => "#".fmt(f),
-            Punct::HashBang => "#!".fmt(f),
-            Punct::Lt => "<".fmt(f),
-            Punct::LtEq => "<=".fmt(f),
-            Punct::LtLt => "<<".fmt(f),
-            Punct::LtLtEq => "<<=".fmt(f),
-            Punct::Minus => "-".fmt(f),
-            Punct::MinusEq => "-=".fmt(f),
-            Punct::Plus => "+".fmt(f),
-            Punct::PlusEq => "+=".fmt(f),
-            Punct::Question => "?".fmt(f),
-            Punct::Rem => "%".fmt(f),
-            Punct::RemEq => "%=".fmt(f),
-            Punct::Semi => ";".fmt(f),
-            Punct::Slash => "/".fmt(f),
-            Punct::SlashEq => "/=".fmt(f),
-            Punct::Star => "*".fmt(f),
-            Punct::StarEq => "*=".fmt(f),
-            Punct::Tilde => "~".fmt(f),
-            Punct::Xor => "^".fmt(f),
-            Punct::XorEq => "^=".fmt(f),
-            Punct::XorXor => "^^".fmt(f),
-        }
-    }
-}

compiler/cl-typeck/Cargo.toml

@@ -10,3 +10,8 @@ publish.workspace = true
 [dependencies]
 cl-ast = { path = "../cl-ast" }
 cl-structures = { path = "../cl-structures" }
+
+[dev-dependencies]
+repline = { version = "*", registry = "soft-fish" }
+cl-lexer = { path = "../cl-lexer" }
+cl-parser = { path = "../cl-parser" }

compiler/cl-typeck/examples/typeck.rs

@@ -0,0 +1,462 @@
+use cl_typeck::{
+    entry::Entry,
+    stage::{
+        infer::{engine::InferenceEngine, error::InferenceError, inference::Inference},
+        *,
+    },
+    table::Table,
+    type_expression::TypeExpression,
+};
+
+use cl_ast::{
+    Expr, Path, Stmt, Ty,
+    ast_visitor::{Fold, Visit},
+    desugar::*,
+};
+use cl_lexer::Lexer;
+use cl_parser::{Parser, inliner::ModuleInliner};
+use cl_structures::intern::string_interner::StringInterner;
+use repline::{error::Error as RlError, prebaked::*};
+use std::{
+    error::Error,
+    path::{self, PathBuf},
+    sync::LazyLock,
+};
+
+// Path to display in standard library errors
+const STDLIB_DISPLAY_PATH: &str = "stdlib/lib.cl";
+// Statically included standard library
+const PREAMBLE: &str = r"
+pub mod std;
+pub use std::preamble::*;
+";
+
+// Colors
+const C_MAIN: &str = C_LISTING;
+const C_RESV: &str = "\x1b[35m";
+const C_CODE: &str = "\x1b[36m";
+const C_BYID: &str = "\x1b[95m";
+const C_ERROR: &str = "\x1b[31m";
+const C_LISTING: &str = "\x1b[38;5;117m";
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let mut prj = Table::default();
+
+    let mut parser = Parser::new("PREAMBLE", Lexer::new(PREAMBLE));
+    let code = match parser.parse() {
+        Ok(code) => code,
+        Err(e) => {
+            eprintln!("{STDLIB_DISPLAY_PATH}:{e}");
+            Err(e)?
+        }
+    };
+    // This code is special - it gets loaded from a hard-coded project directory (for now)
+    let code = inline_modules(code, concat!(env!("CARGO_MANIFEST_DIR"), "/../../stdlib"));
+    let code = cl_ast::desugar::WhileElseDesugar.fold_file(code);
+    Populator::new(&mut prj).visit_file(interned(code));
+
+    for arg in std::env::args().skip(1) {
+        import_file(&mut prj, arg)?;
+    }
+
+    resolve_all(&mut prj)?;
+
+    main_menu(&mut prj)?;
+    Ok(())
+}
+
+fn main_menu(prj: &mut Table) -> Result<(), RlError> {
+    banner();
+    read_and(C_MAIN, "mu>", "? >", |line| {
+        for line in line.trim().split_ascii_whitespace() {
+            match line {
+                "c" | "code" => enter_code(prj)?,
+                "clear" => clear()?,
+                "dump" => dump(prj)?,
+                "d" | "desugar" => live_desugar()?,
+                "e" | "exit" => return Ok(Response::Break),
+                "f" | "file" => import_files(prj)?,
+                "i" | "id" => get_by_id(prj)?,
+                "l" | "list" => list_types(prj),
+                "q" | "query" => query_type_expression(prj)?,
+                "r" | "resolve" => resolve_all(prj)?,
+                "s" | "strings" => print_strings(),
+                "a" | "all" => infer_all(prj)?,
+                "t" | "test" => infer_expression(prj)?,
+                "h" | "help" | "" => {
+                    println!(
+                        "Valid commands are:
+    clear      : Clear the screen
+    code    (c): Enter code to type-check
+    desugar (d): WIP: Test the experimental desugaring passes
+    file    (f): Load files from disk
+    id      (i): Get a type by its type ID
+    list    (l): List all known types
+    query   (q): Query the type system
+    resolve (r): Perform type resolution
+    help    (h): Print this list
+    exit    (e): Exit the program"
+                    );
+                    return Ok(Response::Deny);
+                }
+                _ => Err(r#"Invalid command. Type "help" to see the list of valid commands."#)?,
+            }
+        }
+        Ok(Response::Accept)
+    })
+}
+
+fn enter_code(prj: &mut Table) -> Result<(), RlError> {
+    read_and(C_CODE, "cl>", "? >", |line| {
+        if line.trim().is_empty() {
+            return Ok(Response::Break);
+        }
+        let code = Parser::new("", Lexer::new(line)).parse()?;
+        let code = inline_modules(code, "");
+        let code = WhileElseDesugar.fold_file(code);
+
+        Populator::new(prj).visit_file(interned(code));
+        Ok(Response::Accept)
+    })
+}
+
+fn live_desugar() -> Result<(), RlError> {
+    read_and(C_RESV, "se>", "? >", |line| {
+        let code = Parser::new("", Lexer::new(line)).parse::<Stmt>()?;
+        println!("Raw, as parsed:\n{C_LISTING}{code}\x1b[0m");
+
+        let code = ConstantFolder.fold_stmt(code);
+        println!("ConstantFolder\n{C_LISTING}{code}\x1b[0m");
+
+        let code = SquashGroups.fold_stmt(code);
+        println!("SquashGroups\n{C_LISTING}{code}\x1b[0m");
+
+        let code = WhileElseDesugar.fold_stmt(code);
+        println!("WhileElseDesugar\n{C_LISTING}{code}\x1b[0m");
+
+        let code = NormalizePaths::new().fold_stmt(code);
+        println!("NormalizePaths\n{C_LISTING}{code}\x1b[0m");
+
+        Ok(Response::Accept)
+    })
+}
+
+fn print_strings() {
+    println!("{}", StringInterner::global());
+}
+
+fn query_type_expression(prj: &mut Table) -> Result<(), RlError> {
+    read_and(C_RESV, "ty>", "? >", |line| {
+        if line.trim().is_empty() {
+            return Ok(Response::Break);
+        }
+        // A query is comprised of a Ty and a relative Path
+        let mut p = Parser::new("", Lexer::new(line));
+        let ty: Ty = p.parse()?;
+        let path: Path = p
+            .parse()
+            .map(|p| Path { absolute: false, ..p })
+            .unwrap_or_default();
+        let id = ty.evaluate(prj, prj.root())?;
+        let id = path.evaluate(prj, id)?;
+        pretty_handle(id.to_entry(prj))?;
+        Ok(Response::Accept)
+    })
+}
+
+#[allow(dead_code)]
+fn infer_expression(prj: &mut Table) -> Result<(), RlError> {
+    read_and(C_RESV, "ex>", "!?>", |line| {
+        if line.trim().is_empty() {
+            return Ok(Response::Break);
+        }
+        let mut p = Parser::new("", Lexer::new(line));
+        let e: Expr = p.parse()?;
+        let mut inf = InferenceEngine::new(prj, prj.root());
+        let ty = match exp_terned(e).infer(&mut inf) {
+            Ok(ty) => ty,
+            Err(e) => match e {
+                InferenceError::Mismatch(a, b) => {
+                    eprintln!("Mismatched types: {}, {}", prj.entry(a), prj.entry(b));
+                    return Ok(Response::Deny);
+                }
+                InferenceError::Recursive(a, b) => {
+                    eprintln!("Recursive types: {}, {}", prj.entry(a), prj.entry(b));
+                    return Ok(Response::Deny);
+                }
+                e => Err(e)?,
+            },
+        };
+        eprintln!("--> {}", prj.entry(ty));
+        Ok(Response::Accept)
+    })
+}
+
+fn get_by_id(prj: &mut Table) -> Result<(), RlError> {
+    use cl_parser::parser::Parse;
+    use cl_structures::index_map::MapIndex;
+    use cl_typeck::handle::Handle;
+    read_and(C_BYID, "id>", "? >", |line| {
+        if line.trim().is_empty() {
+            return Ok(Response::Break);
+        }
+        let mut parser = Parser::new("", Lexer::new(line));
+        let def_id = match Parse::parse(&mut parser)? {
+            cl_ast::Literal::Int(int) => int as _,
+            other => Err(format!("Expected integer, got {other}"))?,
+        };
+        let mut path = parser.parse::<cl_ast::Path>().unwrap_or_default();
+        path.absolute = false;
+
+        let handle = Handle::from_usize(def_id).to_entry(prj);
+
+        print!("  > {{{C_LISTING}{handle}\x1b[0m}}");
+        if !path.parts.is_empty() {
+            print!("::{path}")
+        }
+        println!();
+
+        let Some(entry) = handle.nav(&path.parts) else {
+            Err("No results.")?
+        };
+
+        pretty_handle(entry)?;
+
+        Ok(Response::Accept)
+    })
+}
+
+fn resolve_all(table: &mut Table) -> Result<(), Box<dyn Error>> {
+    for (id, error) in import(table) {
+        eprintln!("{error} in {} ({id})", id.to_entry(table))
+    }
+    for handle in table.handle_iter() {
+        if let Err(error) = handle.to_entry_mut(table).categorize() {
+            eprintln!("{error}");
+        }
+    }
+
+    for handle in implement(table) {
+        eprintln!("Unable to reparent {} ({handle})", handle.to_entry(table))
+    }
+
+    println!("...Resolved!");
+    Ok(())
+}
+
+fn infer_all(table: &mut Table) -> Result<(), Box<dyn Error>> {
+    for (id, error) in InferenceEngine::new(table, table.root()).infer_all() {
+        match error {
+            InferenceError::Mismatch(a, b) => {
+                eprint!("Mismatched types: {}, {}", table.entry(a), table.entry(b));
+            }
+            InferenceError::Recursive(a, b) => {
+                eprint!("Recursive types: {}, {}", table.entry(a), table.entry(b));
+            }
+            e => eprint!("{e}"),
+        }
+        eprintln!(" in {id}\n({})\n", id.to_entry(table).source().unwrap())
+    }
+
+    println!("...Inferred!");
+    Ok(())
+}
+
+fn list_types(table: &mut Table) {
+    for handle in table.debug_entry_iter() {
+        let id = handle.id();
+        let kind = handle.kind().unwrap();
+        let name = handle.name().unwrap_or("".into());
+        println!("{id:3}: {name:16}| {kind}: {handle}");
+    }
+}
+
+fn import_file(table: &mut Table, path: impl AsRef<std::path::Path>) -> Result<(), Box<dyn Error>> {
+    let Ok(file) = std::fs::read_to_string(path.as_ref()) else {
+        for file in std::fs::read_dir(path)? {
+            println!("{}", file?.path().display())
+        }
+        return Ok(());
+    };
+
+    let mut parser = Parser::new("", Lexer::new(&file));
+    let code = match parser.parse() {
+        Ok(code) => inline_modules(
+            code,
+            PathBuf::from(path.as_ref()).parent().unwrap_or("".as_ref()),
+        ),
+        Err(e) => {
+            eprintln!("{C_ERROR}{}:{e}\x1b[0m", path.as_ref().display());
+            return Ok(());
+        }
+    };
+
+    let code = cl_ast::desugar::WhileElseDesugar.fold_file(code);
+    Populator::new(table).visit_file(interned(code));
+
+    Ok(())
+}
+
+fn import_files(table: &mut Table) -> Result<(), RlError> {
+    read_and(C_RESV, "fi>", "? >", |line| {
+        let line = line.trim();
+        if line.is_empty() {
+            return Ok(Response::Break);
+        }
+        let Ok(file) = std::fs::read_to_string(line) else {
+            for file in std::fs::read_dir(line)? {
+                println!("{}", file?.path().display())
+            }
+            return Ok(Response::Accept);
+        };
+
+        let mut parser = Parser::new("", Lexer::new(&file));
+        let code = match parser.parse() {
+            Ok(code) => inline_modules(code, PathBuf::from(line).parent().unwrap_or("".as_ref())),
+            Err(e) => {
+                eprintln!("{C_ERROR}{line}:{e}\x1b[0m");
+                return Ok(Response::Deny);
+            }
+        };
+
+        Populator::new(table).visit_file(interned(code));
+
+        println!("...Imported!");
+        Ok(Response::Accept)
+    })
+}
+
+fn pretty_handle(entry: Entry) -> Result<(), std::io::Error> {
+    use std::io::Write;
+    let mut out = std::io::stdout().lock();
+    let Some(kind) = entry.kind() else {
+        return writeln!(out, "{entry}");
+    };
+    write!(out, "{C_LISTING}{kind}")?;
+
+    if let Some(name) = entry.name() {
+        write!(out, " {name}")?;
+    }
+    writeln!(out, "\x1b[0m ({}): {entry}", entry.id())?;
+
+    if let Some(parent) = entry.parent() {
+        writeln!(
+            out,
+            "- {C_LISTING}Parent\x1b[0m: {parent} ({})",
+            parent.id()
+        )?;
+    }
+
+    if let Some(span) = entry.span() {
+        writeln!(
+            out,
+            "- {C_LISTING}Span:\x1b[0m ({}, {})",
+            span.head, span.tail
+        )?;
+    }
+
+    match entry.meta() {
+        Some(meta) if !meta.is_empty() => {
+            writeln!(out, "- {C_LISTING}Meta:\x1b[0m")?;
+            for meta in meta {
+                writeln!(out, "  - {meta}")?;
+            }
+        }
+        _ => {}
+    }
+
+    if let Some(children) = entry.children() {
+        writeln!(out, "- {C_LISTING}Children:\x1b[0m")?;
+        for (name, child) in children {
+            writeln!(
+                out,
+                "  - {C_LISTING}{name}\x1b[0m ({child}): {}",
+                entry.with_id(*child)
+            )?
+        }
+    }
+
+    if let Some(imports) = entry.imports() {
+        writeln!(out, "- {C_LISTING}Imports:\x1b[0m")?;
+        for (name, child) in imports {
+            writeln!(
+                out,
+                "  - {C_LISTING}{name}\x1b[0m ({child}): {}",
+                entry.with_id(*child)
+            )?
+        }
+    }
+
+    Ok(())
+}
+
+fn inline_modules(code: cl_ast::File, path: impl AsRef<path::Path>) -> cl_ast::File {
+    match ModuleInliner::new(path).inline(code) {
+        Err((code, io, parse)) => {
+            for (file, error) in io {
+                eprintln!("{}:{error}", file.display());
+            }
+            for (file, error) in parse {
+                eprintln!("{}:{error}", file.display());
+            }
+            code
+        }
+        Ok(code) => code,
+    }
+}
+
+fn dump(table: &Table) -> Result<(), Box<dyn Error>> {
+    fn dump_recursive(
+        name: cl_ast::Sym,
+        entry: Entry,
+        depth: usize,
+        to_file: &mut std::fs::File,
+    ) -> std::io::Result<()> {
+        use std::io::Write;
+        write!(to_file, "{:w$}{name}: {entry}", "", w = depth)?;
+        if let Some(children) = entry.children() {
+            writeln!(to_file, " {{")?;
+            for (name, child) in children {
+                dump_recursive(*name, entry.with_id(*child), depth + 2, to_file)?;
+            }
+            write!(to_file, "{:w$}}}", "", w = depth)?;
+        }
+        writeln!(to_file)
+    }
+
+    let mut file = std::fs::File::create("typeck-table.ron")?;
+    dump_recursive("root".into(), table.root_entry(), 0, &mut file)?;
+    Ok(())
+}
+
+fn clear() -> Result<(), Box<dyn Error>> {
+    println!("\x1b[H\x1b[2J");
+    banner();
+    Ok(())
+}
+
+fn banner() {
+    println!(
+        "--- {} v{} 💪🦈 ---",
+        env!("CARGO_BIN_NAME"),
+        env!("CARGO_PKG_VERSION"),
+    );
+}
+
+/// Interns a [File](cl_ast::File), returning a static reference to it.
+fn interned(file: cl_ast::File) -> &'static cl_ast::File {
+    use cl_structures::intern::typed_interner::TypedInterner;
+    static INTERNER: LazyLock<TypedInterner<'static, cl_ast::File>> =
+        LazyLock::new(Default::default);
+
+    INTERNER.get_or_insert(file).to_ref()
+}
+
+/// Interns an [Expr](cl_ast::Expr), returning a static reference to it.
+fn exp_terned(expr: cl_ast::Expr) -> &'static cl_ast::Expr {
+    use cl_structures::intern::typed_interner::TypedInterner;
+    static INTERNER: LazyLock<TypedInterner<'static, cl_ast::Expr>> =
+        LazyLock::new(Default::default);
+
+    INTERNER.get_or_insert(expr).to_ref()
+}

compiler/cl-typeck/src/entry.rs

@@ -0,0 +1,212 @@
+//! An [Entry] is an accessor for [nodes](Handle) in a [Table].
+//!
+//! There are two kinds of entry:
+//! - [Entry]: Provides getters for an entry's fields, and an implementation of
+//!   [Display](std::fmt::Display)
+//! - [EntryMut]: Provides setters for an entry's fields, and an [`as_ref`](EntryMut::as_ref) method
+//!   to demote to an [Entry].
+
+use std::collections::HashMap;
+
+use cl_ast::{Expr, Meta, PathPart, Sym};
+use cl_structures::span::Span;
+
+use crate::{
+    handle::Handle,
+    source::Source,
+    stage::categorize as cat,
+    table::{NodeKind, Table},
+    type_expression::{self as tex, TypeExpression},
+    type_kind::TypeKind,
+};
+
+mod debug;
+mod display;
+
+impl Handle {
+    pub const fn to_entry<'t, 'a>(self, table: &'t Table<'a>) -> Entry<'t, 'a> {
+        Entry { id: self, table }
+    }
+    pub fn to_entry_mut<'t, 'a>(self, table: &'t mut Table<'a>) -> EntryMut<'t, 'a> {
+        EntryMut { id: self, table }
+    }
+}
+
+pub struct Entry<'t, 'a> {
+    table: &'t Table<'a>,
+    id: Handle,
+}
+
+macro_rules! impl_entry_ {
+    () => {
+        pub const fn id(&self) -> Handle {
+            self.id
+        }
+
+        pub const fn inner(&'t self) -> &'t Table<'a> {
+            self.table
+        }
+
+        pub fn kind(&self) -> Option<&NodeKind> {
+            self.table.kind(self.id)
+        }
+
+        pub const fn root(&self) -> Handle {
+            self.table.root()
+        }
+
+        pub fn children(&self) -> Option<&HashMap<Sym, Handle>> {
+            self.table.children(self.id)
+        }
+
+        pub fn imports(&self) -> Option<&HashMap<Sym, Handle>> {
+            self.table.imports(self.id)
+        }
+
+        pub fn bodies(&self) -> Option<&'a Expr> {
+            self.table.body(self.id)
+        }
+
+        pub fn span(&self) -> Option<&Span> {
+            self.table.span(self.id)
+        }
+
+        pub fn meta(&self) -> Option<&[Meta]> {
+            self.table.meta(self.id)
+        }
+
+        pub fn source(&self) -> Option<&Source<'a>> {
+            self.table.source(self.id)
+        }
+
+        pub fn name(&self) -> Option<Sym> {
+            self.table.name(self.id)
+        }
+    };
+}
+
+impl<'t, 'a> Entry<'t, 'a> {
+    pub const fn new(table: &'t Table<'a>, id: Handle) -> Self {
+        Self { table, id }
+    }
+
+    impl_entry_!();
+
+    pub const fn with_id(&self, id: Handle) -> Entry<'t, 'a> {
+        Self { table: self.table, id }
+    }
+
+    pub fn nav(&self, path: &[PathPart]) -> Option<Entry<'t, 'a>> {
+        Some(Entry { id: self.table.nav(self.id, path)?, table: self.table })
+    }
+
+    pub fn parent(&self) -> Option<Entry<'t, 'a>> {
+        Some(Entry { id: *self.table.parent(self.id)?, ..*self })
+    }
+
+    pub fn ty(&self) -> Option<&'t TypeKind> {
+        self.table.ty(self.id)
+    }
+
+    pub fn impl_target(&self) -> Option<Entry<'_, 'a>> {
+        Some(Entry { id: self.table.impl_target(self.id)?, ..*self })
+    }
+
+    pub fn selfty(&self) -> Option<Entry<'_, 'a>> {
+        Some(Entry { id: self.table.selfty(self.id)?, ..*self })
+    }
+}
+
+#[derive(Debug)]
+pub struct EntryMut<'t, 'a> {
+    table: &'t mut Table<'a>,
+    id: Handle,
+}
+
+impl<'t, 'a> EntryMut<'t, 'a> {
+    pub fn new(table: &'t mut Table<'a>, id: Handle) -> Self {
+        Self { table, id }
+    }
+
+    impl_entry_!();
+
+    pub fn ty(&self) -> Option<&TypeKind> {
+        self.table.ty(self.id)
+    }
+
+    pub fn inner_mut(&mut self) -> &mut Table<'a> {
+        self.table
+    }
+
+    pub fn as_ref(&self) -> Entry<'_, 'a> {
+        Entry { table: self.table, id: self.id }
+    }
+
+    /// Evaluates a [TypeExpression] in this entry's context
+    pub fn evaluate<Out>(&mut self, ty: &impl TypeExpression<Out>) -> Result<Out, tex::Error> {
+        let Self { table, id } = self;
+        ty.evaluate(table, *id)
+    }
+
+    pub fn categorize(&mut self) -> Result<(), cat::Error> {
+        cat::categorize(self.table, self.id)
+    }
+
+    /// Constructs a new Handle with the provided parent [Handle]
+    pub fn with_id(&mut self, parent: Handle) -> EntryMut<'_, 'a> {
+        EntryMut { table: self.table, id: parent }
+    }
+
+    pub fn nav(&mut self, path: &[PathPart]) -> Option<EntryMut<'_, 'a>> {
+        Some(EntryMut { id: self.table.nav(self.id, path)?, table: self.table })
+    }
+
+    pub fn new_entry(&mut self, kind: NodeKind) -> EntryMut<'_, 'a> {
+        let id = self.table.new_entry(self.id, kind);
+        self.with_id(id)
+    }
+
+    pub fn add_child(&mut self, name: Sym, child: Handle) -> Option<Handle> {
+        self.table.add_child(self.id, name, child)
+    }
+
+    pub fn set_body(&mut self, body: &'a Expr) -> Option<&'a Expr> {
+        self.table.set_body(self.id, body)
+    }
+
+    pub fn set_ty(&mut self, kind: TypeKind) -> Option<TypeKind> {
+        self.table.set_ty(self.id, kind)
+    }
+
+    pub fn set_span(&mut self, span: Span) -> Option<Span> {
+        self.table.set_span(self.id, span)
+    }
+
+    pub fn set_meta(&mut self, meta: &'a [Meta]) -> Option<&'a [Meta]> {
+        self.table.set_meta(self.id, meta)
+    }
+
+    pub fn set_source(&mut self, source: Source<'a>) -> Option<Source<'a>> {
+        self.table.set_source(self.id, source)
+    }
+
+    pub fn set_impl_target(&mut self, target: Handle) -> Option<Handle> {
+        self.table.set_impl_target(self.id, target)
+    }
+
+    pub fn mark_unchecked(&mut self) {
+        self.table.mark_unchecked(self.id)
+    }
+
+    pub fn mark_use_item(&mut self) {
+        self.table.mark_use_item(self.id)
+    }
+
+    pub fn mark_impl_item(&mut self) {
+        self.table.mark_impl_item(self.id)
+    }
+
+    pub fn mark_lang_item(&mut self, lang_item: &'static str) {
+        self.table.mark_lang_item(lang_item, self.id)
+    }
+}

compiler/cl-typeck/src/entry/debug.rs

@@ -0,0 +1,33 @@
+//! [std::fmt::Debug] implementation for [Entry]
+
+use super::Entry;
+
+impl std::fmt::Debug for Entry<'_, '_> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        // virtual fields
+        let mut ds = f.debug_struct("Entry");
+        if let Some(name) = self.name() {
+            ds.field("name", &name.to_ref());
+        }
+        ds.field("kind", &self.kind());
+        if let Some(ty) = self.ty() {
+            ds.field("type", ty);
+        }
+        if let Some(meta) = self.meta() {
+            ds.field("meta", &meta);
+        }
+        if let Some(body) = self.bodies() {
+            ds.field("body", body);
+        }
+        if let Some(children) = self.children() {
+            ds.field("children", children);
+        }
+        if let Some(imports) = self.imports() {
+            ds.field("imports", imports);
+        }
+        // if let Some(source) = self.source() {
+        //     ds.field("source", source);
+        // }
+        ds.field("implements", &self.impl_target()).finish()
+    }
+}

compiler/cl-typeck/src/entry/display.rs

@@ -0,0 +1,100 @@
+use super::*;
+use crate::{format_utils::*, type_kind::Adt};
+use std::fmt::{self, Write};
+
+/// Printing the name of a named type stops infinite recursion
+fn write_name_or(h: Entry, f: &mut impl Write) -> fmt::Result {
+    match h.name() {
+        Some(name) => write!(f, "{name}"),
+        None => write!(f, "{h}"),
+    }
+}
+
+impl fmt::Display for Entry<'_, '_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let Some(&kind) = self.kind() else {
+            return write!(f, "<invalid type: {}>", self.id);
+        };
+
+        if let Some(ty) = self.ty() {
+            match ty {
+                TypeKind::Inferred => write!(f, "<_{}>", self.id),
+                TypeKind::Variable => write!(f, "<?{}>", self.id),
+                TypeKind::Instance(id) => write!(f, "{}", self.with_id(*id)),
+                TypeKind::Primitive(kind) => write!(f, "{kind}"),
+                TypeKind::Adt(adt) => write_adt(adt, self, f),
+                &TypeKind::Ref(id) => {
+                    f.write_str("&")?;
+                    let h_id = self.with_id(id);
+                    write_name_or(h_id, f)
+                }
+                &TypeKind::Ptr(id) => {
+                    f.write_str("*")?;
+                    let h_id = self.with_id(id);
+                    write_name_or(h_id, f)
+                }
+                TypeKind::Slice(id) => {
+                    write_name_or(self.with_id(*id), &mut f.delimit_with("[", "]"))
+                }
+                &TypeKind::Array(t, cnt) => {
+                    let mut f = f.delimit_with("[", "]");
+                    write_name_or(self.with_id(t), &mut f)?;
+                    write!(f, "; {cnt}")
+                }
+                TypeKind::Tuple(ids) => {
+                    let mut f = f.delimit_with("(", ")");
+                    for (index, &id) in ids.iter().enumerate() {
+                        if index > 0 {
+                            write!(f, ", ")?;
+                        }
+                        write_name_or(self.with_id(id), &mut f)?;
+                    }
+                    Ok(())
+                }
+                TypeKind::FnSig { args, rety } => {
+                    write!(f, "fn {} -> ", self.with_id(*args))?;
+                    write_name_or(self.with_id(*rety), f)
+                }
+                TypeKind::Module => write!(f, "module?"),
+            }
+        } else {
+            match kind {
+                NodeKind::Type
+                | NodeKind::Const
+                | NodeKind::Static
+                | NodeKind::Temporary
+                | NodeKind::Let => write!(f, "WARNING: NO TYPE ASSIGNED FOR {}", self.id),
+                _ => write!(f, "{kind}"),
+            }
+        }
+    }
+}
+
+fn write_adt(adt: &Adt, h: &Entry, f: &mut impl Write) -> fmt::Result {
+    match adt {
+        Adt::Enum(variants) => {
+            let mut variants = variants.iter();
+            separate(", ", || {
+                variants.next().map(|(name, def)| {
+                    move |f: &mut Delimit<_>| write!(f, "{name}: {}", h.with_id(*def))
+                })
+            })(f.delimit_with("enum {", "}"))
+        }
+        Adt::Struct(members) => {
+            let mut members = members.iter();
+            separate(", ", || {
+                let (name, vis, id) = members.next()?;
+                Some(move |f: &mut Delimit<_>| write!(f, "{vis}{name}: {}", h.with_id(*id)))
+            })(f.delimit_with("struct {", "}"))
+        }
+        Adt::TupleStruct(members) => {
+            let mut members = members.iter();
+            separate(", ", || {
+                let (vis, def) = members.next()?;
+                Some(move |f: &mut Delimit<_>| write!(f, "{vis}{}", h.with_id(*def)))
+            })(f.delimit_with("struct (", ")"))
+        }
+        Adt::UnitStruct => write!(f, "struct"),
+        Adt::Union(_) => todo!("Display union types"),
+    }
+}

compiler/cl-typeck/src/format_utils.rs

@@ -0,0 +1,20 @@
+pub use cl_ast::format::*;
+use std::{fmt, iter};
+
+/// Separates the items yielded by iterating the provided function
+pub const fn separate<'f, 's, Item, F, W>(sep: &'s str, t: F) -> impl FnOnce(W) -> fmt::Result + 's
+where
+    Item: FnMut(&mut W) -> fmt::Result,
+    F: FnMut() -> Option<Item> + 's,
+    W: fmt::Write,
+{
+    move |mut f| {
+        for (idx, mut disp) in iter::from_fn(t).enumerate() {
+            if idx > 0 {
+                f.write_str(sep)?;
+            }
+            disp(&mut f)?;
+        }
+        Ok(())
+    }
+}

compiler/cl-typeck/src/handle.rs

@@ -0,0 +1,15 @@
+//! A [Handle] uniquely represents an entry in the [Table](crate::table::Table)
+
+use cl_structures::index_map::*;
+
+// define the index types
+make_index! {
+    /// Uniquely represents an entry in the [Table](crate::table::Table)
+    Handle,
+}
+
+impl std::fmt::Display for Handle {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.0.fmt(f)
+    }
+}

compiler/cl-typeck/src/lib.rs

@@ -0,0 +1,74 @@
+//! # The Conlang Type Checker
+//!
+//! As a statically typed language, Conlang requires a robust type checker to enforce correctness.
+//!
+//! This crate is a major work-in-progress.
+//!
+//! # The [Table](table::Table)™
+//! A directed graph of nodes and their dependencies.
+//!
+//! Contains [item definitions](handle) and [type expression](type_expression) information.
+//!
+//! *Every* item is itself a module, and can contain arbitrarily nested items
+//! as part of the item graph
+//!
+//! The table, additionally, has some queues for use in external algorithms,
+//! detailed in the [stage] module.
+//!
+//! # Namespaces
+//! Each item in the graph is given its own namespace, which is further separated into
+//! two distinct parts:
+//! - Children of an item are direct descendents (i.e. their `parent` is a handle to the item)
+//! - Imports of an item are indirect descendents created by `use` or `impl` directives. They are
+//!   shadowed by Children with the same name.
+//!
+//! # Order of operations:
+//! For order-of-operations information, see the [stage] module.
+#![warn(clippy::all)]
+
+pub(crate) mod format_utils;
+
+pub mod table;
+
+pub mod handle;
+
+pub mod entry;
+
+pub mod source;
+
+pub mod type_kind;
+
+pub mod type_expression;
+
+pub mod stage {
+    //! Type collection, evaluation, checking, and inference passes.
+    //!
+    //! # Order of operations
+    //! 1. [mod@populate]: Populate the graph with nodes for every named item.
+    //! 2. [mod@import]: Import the `use` nodes discovered in [Stage 1](populate).
+    //! 3. [mod@categorize]: Categorize the nodes according to textual type information.
+    //!    - Creates anonymous types (`fn(T) -> U`, `&T`, `[T]`, etc.) as necessary to fill in the
+    //!      type graph
+    //!    - Creates a new struct type for every enum struct-variant.
+    //! 4. [mod@implement]: Import members of implementation modules into types.
+
+    pub use populate::Populator;
+    /// Stage 1: Populate the graph with nodes.
+    pub mod populate;
+
+    pub use import::import;
+    /// Stage 2: Import the `use` nodes discovered in Stage 1.
+    pub mod import;
+
+    pub use categorize::categorize;
+    /// Stage 3: Categorize the nodes according to textual type information.
+    pub mod categorize;
+
+    pub use implement::implement;
+    /// Stage 4: Import members of `impl` blocks into their corresponding types.
+    pub mod implement;
+
+    // TODO: Make type inference stage 5
+    // TODO: Use the type information stored in the [table]
+    pub mod infer;
+}

compiler/cl-typeck/src/source.rs

@@ -0,0 +1,87 @@
+//! Holds the [Source] of a definition in the AST
+
+use cl_ast::ast::*;
+use std::fmt;
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum Source<'a> {
+    Root,
+    Module(&'a Module),
+    Alias(&'a Alias),
+    Enum(&'a Enum),
+    Variant(&'a Variant),
+    Struct(&'a Struct),
+    Const(&'a Const),
+    Static(&'a Static),
+    Function(&'a Function),
+    Local(&'a Let),
+    Impl(&'a Impl),
+    Use(&'a Use),
+    Ty(&'a TyKind),
+}
+
+impl Source<'_> {
+    pub fn name(&self) -> Option<Sym> {
+        match self {
+            Source::Root => None,
+            Source::Module(v) => Some(v.name),
+            Source::Alias(v) => Some(v.name),
+            Source::Enum(v) => Some(v.name),
+            Source::Variant(v) => Some(v.name),
+            Source::Struct(v) => Some(v.name),
+            Source::Const(v) => Some(v.name),
+            Source::Static(v) => Some(v.name),
+            Source::Function(v) => Some(v.name),
+            Source::Local(_) => None,
+            Source::Impl(_) | Source::Use(_) | Source::Ty(_) => None,
+        }
+    }
+
+    /// Returns `true` if this [Source] defines a named value
+    pub fn is_named_value(&self) -> bool {
+        matches!(self, Self::Const(_) | Self::Static(_) | Self::Function(_))
+    }
+
+    /// Returns `true` if this [Source] defines a named type
+    pub fn is_named_type(&self) -> bool {
+        matches!(
+            self,
+            Self::Module(_) | Self::Alias(_) | Self::Enum(_) | Self::Struct(_)
+        )
+    }
+
+    /// Returns `true` if this [Source] refers to a [Ty] with no name
+    pub fn is_anon_type(&self) -> bool {
+        matches!(self, Self::Ty(_))
+    }
+
+    /// Returns `true` if this [Source] refers to an [Impl] block
+    pub fn is_impl(&self) -> bool {
+        matches!(self, Self::Impl(_))
+    }
+
+    /// Returns `true` if this [Source] refers to a [Use] import
+    pub fn is_use_import(&self) -> bool {
+        matches!(self, Self::Use(_))
+    }
+}
+
+impl fmt::Display for Source<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Root => "🌳 root 🌳".fmt(f),
+            Self::Module(arg0) => arg0.fmt(f),
+            Self::Alias(arg0) => arg0.fmt(f),
+            Self::Enum(arg0) => arg0.fmt(f),
+            Self::Variant(arg0) => arg0.fmt(f),
+            Self::Struct(arg0) => arg0.fmt(f),
+            Self::Const(arg0) => arg0.fmt(f),
+            Self::Static(arg0) => arg0.fmt(f),
+            Self::Function(arg0) => arg0.fmt(f),
+            Self::Impl(arg0) => arg0.fmt(f),
+            Self::Use(arg0) => arg0.fmt(f),
+            Self::Ty(arg0) => arg0.fmt(f),
+            Self::Local(arg0) => arg0.fmt(f),
+        }
+    }
+}

compiler/cl-typeck/src/stage/categorize.rs

@@ -0,0 +1,187 @@
+//! Categorizes an entry in a table according to its embedded type information
+#![allow(unused)]
+use crate::{
+    entry::EntryMut,
+    handle::Handle,
+    source::Source,
+    table::{NodeKind, Table},
+    type_expression::{Error as TypeEval, TypeExpression},
+    type_kind::{Adt, TypeKind},
+};
+use cl_ast::*;
+
+/// Ensures a type entry exists for the provided handle in the table
+pub fn categorize(table: &mut Table, node: Handle) -> CatResult<()> {
+    let Some(source) = table.source(node) else {
+        return Ok(());
+    };
+
+    match source {
+        Source::Variant(v) => cat_variant(table, node, v)?,
+        Source::Struct(s) => cat_struct(table, node, s)?,
+        Source::Const(c) => cat_const(table, node, c)?,
+        Source::Static(s) => cat_static(table, node, s)?,
+        Source::Function(f) => cat_function(table, node, f)?,
+        Source::Local(l) => cat_local(table, node, l)?,
+        Source::Impl(i) => cat_impl(table, node, i)?,
+        // Source::Alias(_) => {table.mark_unchecked(node)},
+        _ => return Ok(()),
+    }
+    Ok(())
+}
+
+fn parent(table: &Table, node: Handle) -> Handle {
+    table.parent(node).copied().unwrap_or(node)
+}
+
+fn cat_struct(table: &mut Table, node: Handle, s: &Struct) -> CatResult<()> {
+    let Struct { name: _, gens: _, kind } = s;
+    // TODO: Generics
+    let kind = match kind {
+        StructKind::Empty => TypeKind::Adt(Adt::UnitStruct),
+        StructKind::Tuple(types) => {
+            let mut out = vec![];
+            for ty in types {
+                out.push((Visibility::Public, ty.evaluate(table, node)?))
+            }
+            TypeKind::Adt(Adt::TupleStruct(out))
+        }
+        StructKind::Struct(members) => {
+            let mut out = vec![];
+            for m in members {
+                out.push(cat_member(table, node, m)?)
+            }
+            TypeKind::Adt(Adt::Struct(out))
+        }
+    };
+
+    table.set_ty(node, kind);
+    Ok(())
+}
+
+fn cat_member(
+    table: &mut Table,
+    node: Handle,
+    m: &StructMember,
+) -> CatResult<(Sym, Visibility, Handle)> {
+    let StructMember { vis, name, ty } = m;
+    Ok((*name, *vis, ty.evaluate(table, node)?))
+}
+
+fn cat_enum<'a>(_table: &mut Table<'a>, _node: Handle, e: &'a Enum) -> CatResult<()> {
+    let Enum { name: _, gens: _, variants: _ } = e;
+    // table.set_ty(node, kind);
+    Ok(())
+}
+
+fn cat_variant<'a>(table: &mut Table<'a>, node: Handle, v: &'a Variant) -> CatResult<()> {
+    let Variant { name, kind, body } = v;
+    let parent = table.parent(node).copied().unwrap_or(table.root());
+    match (kind) {
+        (StructKind::Empty) => Ok(()),
+        (StructKind::Empty) => Ok(()),
+        (StructKind::Tuple(ty)) => {
+            let ty = TypeKind::Adt(Adt::TupleStruct(
+                ty.iter()
+                    .map(|ty| ty.evaluate(table, node).map(|ty| (Visibility::Public, ty)))
+                    .collect::<Result<_, _>>()?,
+            ));
+            table.set_ty(node, ty);
+            Ok(())
+        }
+        (StructKind::Struct(members)) => {
+            let mut out = vec![];
+            for StructMember { vis, name, ty } in members {
+                let ty = ty.evaluate(table, node)?;
+                out.push((*name, *vis, ty));
+
+                let mut this = node.to_entry_mut(table);
+                let mut child = this.new_entry(NodeKind::Type);
+                child.set_source(Source::Variant(v));
+                child.set_ty(TypeKind::Instance(ty));
+
+                let child = child.id();
+                this.add_child(*name, child);
+            }
+
+            table.set_ty(node, TypeKind::Adt(Adt::Struct(out)));
+            Ok(())
+        }
+    }
+}
+
+fn cat_const(table: &mut Table, node: Handle, c: &Const) -> CatResult<()> {
+    let parent = parent(table, node);
+    let kind = TypeKind::Instance(
+        c.ty.evaluate(table, parent)
+            .map_err(|e| Error::TypeEval(e, " while categorizing a const"))?,
+    );
+    table.set_ty(node, kind);
+    Ok(())
+}
+
+fn cat_static(table: &mut Table, node: Handle, s: &Static) -> CatResult<()> {
+    let parent = parent(table, node);
+    let kind = TypeKind::Instance(
+        s.ty.evaluate(table, parent)
+            .map_err(|e| Error::TypeEval(e, " while categorizing a static"))?,
+    );
+    table.set_ty(node, kind);
+    Ok(())
+}
+
+fn cat_function(table: &mut Table, node: Handle, f: &Function) -> CatResult<()> {
+    let kind = TypeKind::Instance(
+        f.sign
+            .evaluate(table, node)
+            .map_err(|e| Error::TypeEval(e, " while categorizing a function"))?,
+    );
+    table.set_ty(node, kind);
+    Ok(())
+}
+
+fn cat_local(table: &mut Table, node: Handle, l: &Let) -> CatResult<()> {
+    let parent = parent(table, node);
+    if let Some(ty) = &l.ty {
+        let kind = ty
+            .evaluate(table, parent)
+            .map_err(|e| Error::TypeEval(e, " while categorizing a let binding"))?;
+        table.set_ty(node, TypeKind::Instance(kind));
+    }
+    Ok(())
+}
+
+fn cat_impl(table: &mut Table, node: Handle, i: &Impl) -> CatResult<()> {
+    let parent = parent(table, node);
+    let Impl { gens, target, body: _ } = i;
+    let target = match target {
+        ImplKind::Type(t) => t.evaluate(table, parent),
+        ImplKind::Trait { impl_trait: _, for_type: t } => t.evaluate(table, parent),
+    }?;
+
+    table.set_impl_target(node, target);
+    Ok(())
+}
+
+type CatResult<T> = Result<T, Error>;
+
+#[derive(Clone, Debug)]
+pub enum Error {
+    BadMeta(Meta),
+    TypeEval(TypeEval, &'static str),
+}
+
+impl From<TypeEval> for Error {
+    fn from(value: TypeEval) -> Self {
+        Error::TypeEval(value, "")
+    }
+}
+
+impl std::fmt::Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Error::BadMeta(meta) => write!(f, "Unknown attribute: #[{meta}]"),
+            Error::TypeEval(e, during) => write!(f, "{e}{during}"),
+        }
+    }
+}

compiler/cl-typeck/src/stage/implement.rs

@@ -0,0 +1,23 @@
+use crate::{handle::Handle, table::Table};
+
+pub fn implement(table: &mut Table) -> Vec<Handle> {
+    let pending = std::mem::take(&mut table.impls);
+    let mut errors = vec![];
+    for node in pending {
+        if let Err(e) = impl_one(table, node) {
+            errors.push(e);
+        }
+    }
+    errors
+}
+
+pub fn impl_one(table: &mut Table, node: Handle) -> Result<(), Handle> {
+    let Some(target) = table.impl_target(node) else {
+        Err(node)?
+    };
+    if let Some(children) = table.children.get_mut(&node) {
+        let children = children.clone();
+        table.children.entry(target).or_default().extend(children);
+    }
+    Ok(())
+}

compiler/cl-typeck/src/stage/import.rs

@@ -0,0 +1,158 @@
+//! An algorithm for importing external nodes
+
+use crate::{
+    handle::Handle,
+    source::Source,
+    table::{NodeKind, Table},
+};
+use cl_ast::{PathPart, Sym, Use, UseTree};
+use core::slice;
+use std::{collections::HashSet, mem};
+
+type Seen = HashSet<Handle>;
+
+pub fn import<'a>(table: &mut Table<'a>) -> Vec<(Handle, Error<'a>)> {
+    let pending = mem::take(&mut table.uses);
+
+    let mut seen = Seen::new();
+    let mut failed = vec![];
+    for import in pending {
+        let Err(e) = import_one(table, import, &mut seen) else {
+            continue;
+        };
+        if let Error::NotFound(_, _) = e {
+            table.mark_use_item(import)
+        }
+        failed.push((import, e));
+    }
+    failed
+}
+
+fn import_one<'a>(table: &mut Table<'a>, item: Handle, seen: &mut Seen) -> UseResult<'a, ()> {
+    if !seen.insert(item) {
+        return Ok(());
+    }
+
+    let Some(NodeKind::Use) = table.kind(item) else {
+        Err(Error::ItsNoUse)?
+    };
+    let Some(&dst) = table.parent(item) else {
+        Err(Error::NoParents)?
+    };
+    let Some(code) = table.source(item) else {
+        Err(Error::NoSource)?
+    };
+    let &Source::Use(tree) = code else {
+        Err(Error::BadSource(*code))?
+    };
+    let Use { absolute, tree } = tree;
+
+    import_tree(
+        table,
+        if !absolute { dst } else { table.root() },
+        dst,
+        tree,
+        seen,
+    )
+}
+
+fn import_tree<'a>(
+    table: &mut Table<'a>,
+    src: Handle,
+    dst: Handle,
+    tree: &UseTree,
+    seen: &mut Seen,
+) -> UseResult<'a, ()> {
+    match tree {
+        UseTree::Tree(trees) => trees
+            .iter()
+            .try_for_each(|tree| import_tree(table, src, dst, tree, seen)),
+        UseTree::Path(part, rest) => {
+            let source = table
+                .nav(src, slice::from_ref(part))
+                .ok_or(Error::NotFound(src, *part))?;
+            import_tree(table, source, dst, rest, seen)
+        }
+        UseTree::Alias(src_name, dst_name) => {
+            import_name(table, src, src_name, dst, dst_name, seen)
+        }
+        UseTree::Name(src_name) => import_name(table, src, src_name, dst, src_name, seen),
+        UseTree::Glob => import_glob(table, src, dst, seen),
+    }
+}
+
+fn import_glob<'a>(
+    table: &mut Table<'a>,
+    src: Handle,
+    dst: Handle,
+    seen: &mut Seen,
+) -> UseResult<'a, ()> {
+    let Table { children, imports, .. } = table;
+
+    if let Some(c) = children.get(&src) {
+        imports.entry(dst).or_default().extend(c)
+    }
+
+    import_deps(table, src, seen)?;
+
+    let Table { imports, .. } = table;
+
+    // Importing imports requires some extra work, since we can't `get_many_mut`
+    if let Some(i) = imports.get(&src) {
+        let uses: Vec<_> = i.iter().map(|(&k, &v)| (k, v)).collect();
+        imports.entry(dst).or_default().extend(uses);
+    }
+
+    Ok(())
+}
+
+fn import_name<'a>(
+    table: &mut Table<'a>,
+    src: Handle,
+    src_name: &Sym,
+    dst: Handle,
+    dst_name: &Sym,
+    seen: &mut Seen,
+) -> UseResult<'a, ()> {
+    import_deps(table, src, seen)?;
+    match table.get_by_sym(src, src_name) {
+        // TODO: check for new imports clobbering existing imports
+        Some(src_id) => table.add_import(dst, *dst_name, src_id),
+        None => Err(Error::NotFound(src, PathPart::Ident(*src_name)))?,
+    };
+    Ok(())
+}
+
+/// Imports the dependencies of this node
+fn import_deps<'a>(table: &mut Table<'a>, node: Handle, seen: &mut Seen) -> UseResult<'a, ()> {
+    if let Some(items) = table.use_items.get(&node) {
+        let out = items.clone();
+        for item in out {
+            import_one(table, item, seen)?;
+        }
+    }
+    Ok(())
+}
+
+pub type UseResult<'a, T> = Result<T, Error<'a>>;
+
+#[derive(Debug)]
+pub enum Error<'a> {
+    ItsNoUse,
+    NoParents,
+    NoSource,
+    BadSource(Source<'a>),
+    NotFound(Handle, PathPart),
+}
+
+impl std::fmt::Display for Error<'_> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Error::ItsNoUse => write!(f, "Entry is not use"),
+            Error::NoParents => write!(f, "Entry has no parents"),
+            Error::NoSource => write!(f, "Entry has no source"),
+            Error::BadSource(s) => write!(f, "Entry incorrectly marked as use item: {s}"),
+            Error::NotFound(id, part) => write!(f, "Could not traverse {id}::{part}"),
+        }
+    }
+}