cl-typeck: Computer! Define "types!"

WARNING: The type checker is still a MAJOR work in progress. You'll be unable to ignore the stringly-typed error handling, effort duplication, and general poor code quality all around. However, this makes leaps and bounds toward a functional, if primitive, type checker.

Definitions now borrow their data from the AST, reducing needless copies.
- This unfortunately means the REPL has to keep around old ASTs, but... Eh. Probably have to keep those around anyway.

The "char" primitive type has been added. Semantics TBD.

Modules definition, type_kind, and value_kind have been consolidated into one.

Project now keeps track of the set of unnamed (anonymous) types (i.e. tuples, function pointers, references) and will yield them freely.
- Project can now also evaluate arbitrary type expressions via the EvaluableTypeExpression trait.

The NameCollector has been replaced with trait NameCollectable.
- This pass visits each node in the AST which can have an item declaration inside it, and constructs an unevaluated module tree.

The TypeResolver has been replaced with trait TypeResolvable and the function resolve()
- This pass visits each *Def* in the project, and attempts to derive all subtypes.
- It's important to note that for Items, unlike EvaluableTypeExpression, the ID passed into resolve_type is the ID of `self`, not of the parent!

typeck.rs:
- The Conlang "standard library" is included in the binary
- There's a main menu now! Type "help" for options.
- Queries have been upgraded from paths to full type expressions!
  - Querying doesn't currently trigger resolution, but it could!

cl-typeck/src/definition/display.rs

@@ -0,0 +1,162 @@
+//! [Display] implementations for [TypeKind], [Adt], and [Intrinsic]
+
+use super::{Adt, Def, DefKind, Intrinsic, TypeKind, ValueKind};
+use cl_ast::format::FmtPretty;
+use std::{
+    fmt::{self, Display, Write},
+    iter,
+};
+
+fn sep<'f, 's, Item, F>(
+    before: &'s str,
+    after: &'s str,
+    t: F,
+) -> impl FnOnce(&mut fmt::Formatter<'f>) -> fmt::Result + 's
+where
+    Item: FnMut(&mut fmt::Formatter<'f>) -> fmt::Result,
+    F: FnMut() -> Option<Item> + 's,
+{
+    move |f| {
+        f.write_str(before)?;
+        for (idx, mut disp) in iter::from_fn(t).enumerate() {
+            if idx > 0 {
+                f.write_str(", ")?;
+            }
+            disp(f)?;
+        }
+        f.write_str(after)
+    }
+}
+
+impl Display for Def<'_> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self { name, vis, meta, kind, source, module } = self;
+        writeln!(f, "{vis}{name}: ")?;
+        writeln!(f, "kind: {kind}")?;
+        if !meta.is_empty() {
+            writeln!(f, "meta: {meta:?}")?;
+        }
+        if let Some(source) = source {
+            writeln!(f.pretty(), "source: {{\n{source}\n}}")?;
+        }
+        write!(f, "module: {module}")
+    }
+}
+
+impl Display for DefKind<'_> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            DefKind::Undecided => write!(f, "undecided"),
+            DefKind::Impl(id) => write!(f, "impl {id}"),
+            DefKind::Type(kind) => write!(f, "{kind}"),
+            DefKind::Value(kind) => write!(f, "{kind}"),
+        }
+    }
+}
+
+impl std::fmt::Display for ValueKind {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            ValueKind::Const(id) => write!(f, "const ({id})"),
+            ValueKind::Static(id) => write!(f, "static ({id})"),
+            ValueKind::Fn(id) => write!(f, "fn def ({id})"),
+        }
+    }
+}
+
+impl Display for TypeKind<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            TypeKind::Alias(def) => match def {
+                Some(def) => write!(f, "alias to #{def}"),
+                None => f.write_str("type"),
+            },
+            TypeKind::Intrinsic(i) => i.fmt(f),
+            TypeKind::Adt(a) => a.fmt(f),
+            TypeKind::Ref(cnt, def) => {
+                for _ in 0..*cnt {
+                    f.write_str("&")?;
+                }
+                def.fmt(f)
+            }
+            TypeKind::Slice(def) => write!(f, "slice [#{def}]"),
+            TypeKind::Array(def, size) => write!(f, "array [#{def}; {size}]"),
+            TypeKind::Tuple(defs) => {
+                let mut defs = defs.iter();
+                sep("tuple (", ")", || {
+                    let def = defs.next()?;
+                    Some(move |f: &mut fmt::Formatter| write!(f, "#{def}"))
+                })(f)
+            }
+            TypeKind::FnSig { args, rety } => write!(f, "fn (#{args}) -> #{rety}"),
+            TypeKind::Empty => f.write_str("()"),
+            TypeKind::Never => f.write_str("!"),
+            TypeKind::SelfTy => f.write_str("Self"),
+            TypeKind::Module => f.write_str("mod"),
+        }
+    }
+}
+
+impl Display for Adt<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Adt::Enum(variants) => {
+                let mut variants = variants.iter();
+                sep("enum {", "}", || {
+                    let (name, def) = variants.next()?;
+                    Some(move |f: &mut fmt::Formatter| match def {
+                        Some(def) => write!(f, "{name}: #{def}"),
+                        None => write!(f, "{name}"),
+                    })
+                })(f)
+            }
+            Adt::CLikeEnum(variants) => {
+                let mut variants = variants.iter();
+                sep("enum {", "}", || {
+                    let (name, descrim) = variants.next()?;
+                    Some(move |f: &mut fmt::Formatter| write!(f, "{name} = {descrim}"))
+                })(f)
+            }
+            Adt::FieldlessEnum => write!(f, "enum"),
+            Adt::Struct(members) => {
+                let mut members = members.iter();
+                sep("struct {", "}", || {
+                    let (name, vis, def) = members.next()?;
+                    Some(move |f: &mut fmt::Formatter| write!(f, "{vis}{name}: #{def}"))
+                })(f)
+            }
+            Adt::TupleStruct(members) => {
+                let mut members = members.iter();
+                sep("struct (", ")", || {
+                    let (vis, def) = members.next()?;
+                    Some(move |f: &mut fmt::Formatter| write!(f, "{vis}#{def}"))
+                })(f)
+            }
+            Adt::UnitStruct => write!(f, "struct ()"),
+            Adt::Union(variants) => {
+                let mut variants = variants.iter();
+                sep("union {", "}", || {
+                    let (name, def) = variants.next()?;
+                    Some(move |f: &mut fmt::Formatter| write!(f, "{name}: #{def}"))
+                })(f)
+            }
+        }
+    }
+}
+
+impl Display for Intrinsic {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Intrinsic::I8 => f.write_str("i8"),
+            Intrinsic::I16 => f.write_str("i16"),
+            Intrinsic::I32 => f.write_str("i32"),
+            Intrinsic::I64 => f.write_str("i64"),
+            Intrinsic::U8 => f.write_str("u8"),
+            Intrinsic::U16 => f.write_str("u16"),
+            Intrinsic::U32 => f.write_str("u32"),
+            Intrinsic::U64 => f.write_str("u64"),
+            Intrinsic::Bool => f.write_str("bool"),
+            Intrinsic::Char => f.write_str("char"),
+        }
+    }
+}