examples: Adapt examples/yaml to a broken C generator! woo!

compiler/cl-repl/examples/to_c.rs

@@ -0,0 +1,932 @@
+//! 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 yamler::CLangifier;
+pub mod yamler {
+    use crate::yamlify::CLangify;
+    use std::{
+        fmt::Display,
+        io::Write,
+        ops::{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 key(&mut self, name: impl Display) -> Section {
+            print!("{name}");
+            self.indent()
+        }
+    }
+
+    /// 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 yamlify {
+    use std::iter;
+
+    use super::yamler::CLangifier;
+    use cl_ast::*;
+
+    pub trait CLangify {
+        fn print(&self, y: &mut CLangifier);
+    }
+
+    impl CLangify for File {
+        fn print(&self, y: &mut CLangifier) {
+            let File { name, items } = self;
+            // TODO: turn name into include guard
+            y.p("// Generated from ").p(name).endl();
+            y.p(items);
+        }
+    }
+    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.key("Attrs").p(meta);
+            todo!("Attributes");
+        }
+    }
+    impl CLangify for Meta {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { name, kind } = self;
+            y.key("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).endl().endl();
+        }
+    }
+    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 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.key("// 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, sign, bind, body } = self;
+            let TyFn { args, rety } = sign;
+            let types = match args.as_ref() {
+                TyKind::Tuple(TyTuple { types }) => types.as_slice(),
+                TyKind::Empty => &[],
+                _ => panic!("Unsupported function args: {args}"),
+            };
+            match rety {
+                Some(ty) => y.p(ty),
+                None => y.p("void"),
+            }
+            .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, kind } = self;
+            y.p("struct ").p(name).key(" {").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, variants } = self;
+            y.key("enum ").p(name).p(" {").endl();
+            match variants {
+                Some(v) => {
+                    for (idx, variant) in v.iter().enumerate() {
+                        if idx > 0 {
+                            y.p(",").endl();
+                        }
+                        y.p(variant);
+                    }
+                }
+                None => todo!(),
+            }
+            y.endl().p("\n}");
+        }
+    }
+    impl CLangify for Variant {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { name, kind } = self;
+            y.p(name).p(kind);
+        }
+    }
+    impl CLangify for VariantKind {
+        fn print(&self, y: &mut CLangifier) {
+            match self {
+                VariantKind::Plain => y,
+                VariantKind::CLike(v) => y.p(" = ").p(v),
+                VariantKind::Tuple(v) => y.p("/* TODO: ").p(v).p(" */"),
+                VariantKind::Struct(v) => y.p("/* TODO: ").p(v).p(" */"),
+            };
+        }
+    }
+    impl CLangify for Impl {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { target, body } = self;
+            y.key("/* TODO: impl ").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.key("{");
+                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::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.key("continue");
+                }
+            }
+        }
+    }
+    impl CLangify for Quote {
+        fn print(&self, y: &mut CLangifier) {
+            y.key("\"");
+            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.key("(").p(rety).p(" *").p(mutable).p(name).p(")(");
+                    match args.as_ref() {
+                        TyKind::Empty => {}
+                        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::Literal(literal) => y.p(literal),
+                Pattern::Rest(name) => y.p("..").p(name),
+                Pattern::Ref(mutability, pattern) => y.p("&").p(mutability).p(pattern),
+                Pattern::Tuple(patterns) => y.key("Tuple").p(patterns),
+                Pattern::Array(patterns) => y.key("Array").p(patterns),
+                Pattern::Struct(path, items) => {
+                    {
+                        let mut y = y.key("Struct");
+                        y.p(path);
+                        for (name, item) in items {
+                            y.p(name).p(item);
+                        }
+                    }
+                    y
+                }
+                Pattern::TupleStruct(path, items) => {
+                    {
+                        let mut y = y.key("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.key(" { ").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.key("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.key("(").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.key("( ");
+            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.key("(").p(to).p(")");
+            {
+                let mut y = y.key("{ ");
+                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.key("{");
+                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;
+            // TODO: compile time evaluation
+            let ExprKind::Literal(Literal::Int(count)) = &repeat.kind else {
+                panic!("Unsupported repeat count: {repeat}");
+            };
+            {
+                let mut y = y.key("{");
+                y.endl();
+                for idx in 0..*count {
+                    if idx > 0 {
+                        y.p(", ");
+                    }
+                    y.p(value);
+                }
+            }
+            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.key("while(1) { if (").p(cond).p(")").p(pass);
+            if let Some(fail) = fail {
+                y.p("else { ").p(fail).p("; break; }");
+            }
+        }
+    }
+    impl CLangify for Else {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { body } = self;
+            if let Some(body) = body {
+                y.key("else ").p(body);
+            }
+        }
+    }
+    impl CLangify for If {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { cond, pass, fail } = self;
+            y.p("(").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.key("break ").p(body);
+        }
+    }
+    impl CLangify for Return {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { body } = self;
+            y.key("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 } = self;
+            y.p(kind);
+        }
+    }
+    impl CLangify for TyKind {
+        fn print(&self, y: &mut CLangifier) {
+            match self {
+                TyKind::Never => y.p("Never"),
+                TyKind::Empty => y.p("Empty"),
+                TyKind::Infer => y.p("Any"),
+                TyKind::Path(t) => y.p(t),
+                TyKind::Tuple(t) => y.p(t),
+                TyKind::Ref(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::SelfKw => y.p("self"),
+                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.key("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 TyFn {
+        fn print(&self, y: &mut CLangifier) {
+            let Self { args, rety } = self;
+            // TODO: function pointer syntax
+            y.key("*(").p(rety).p(")(");
+            match args.as_ref() {
+                TyKind::Empty => y,
+                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
+    }
+}