cl-ast: Re-add(?) the Infer type-pattern

compiler/cl-ast/src/ast.rs

@@ -221,6 +221,7 @@ pub struct Ty {
 pub enum TyKind {
     Never,
     Empty,
+    Infer,
     Path(Path),
     Array(TyArray),
     Slice(TySlice),

compiler/cl-ast/src/ast_impl.rs

@@ -149,7 +149,7 @@ mod display {
                     ' '.fmt(f)?;
                     write!(f.delimit(BRACES), "{items}")
                 }
-                None => Ok(())
+                None => Ok(()),
             }
         }
     }
@@ -290,6 +290,7 @@ mod display {
             match self {
                 TyKind::Never => "!".fmt(f),
                 TyKind::Empty => "()".fmt(f),
+                TyKind::Infer => "_".fmt(f),
                 TyKind::Path(v) => v.fmt(f),
                 TyKind::Array(v) => v.fmt(f),
                 TyKind::Slice(v) => v.fmt(f),

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

@@ -523,6 +523,7 @@ pub fn or_fold_ty_kind<F: Fold + ?Sized>(folder: &mut F, kind: TyKind) -> TyKind
     match kind {
         TyKind::Never => TyKind::Never,
         TyKind::Empty => TyKind::Empty,
+        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)),

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

@@ -455,6 +455,7 @@ pub fn or_visit_ty_kind<'a, V: Visit<'a>>(visitor: &mut V, kind: &'a TyKind) {
     match kind {
         TyKind::Never => {}
         TyKind::Empty => {}
+        TyKind::Infer => {}
         TyKind::Path(p) => visitor.visit_path(p),
         TyKind::Array(t) => visitor.visit_ty_array(t),
         TyKind::Slice(t) => visitor.visit_ty_slice(t),

compiler/cl-interpret/src/interpret.rs

@@ -7,7 +7,6 @@
 
 use super::*;
 use cl_ast::{ast_visitor::Visit, *};
-use cl_structures::intern::interned::Interned;
 use std::borrow::Borrow;
 /// A work-in-progress tree walk interpreter for Conlang
 pub trait Interpret {

compiler/cl-parser/src/parser.rs

@@ -496,7 +496,7 @@ impl Parse<'_> for TypedParam {
             if p.match_type(TokenKind::Colon, Parsing::Param).is_ok() {
                 TyKind::parse(p)?
             } else {
-                TyKind::Path(Path::from(Sym::from("_")))
+                TyKind::Infer
             },
         ))
     }
@@ -742,7 +742,14 @@ impl Parse<'_> for TyKind {
                 }
             }
             TokenKind::Fn => TyFn::parse(p)?.into(),
-            path_like!() => Path::parse(p)?.into(),
+            path_like!() => {
+                let path = Path::parse(p)?;
+                if path.is_sinkhole() {
+                    TyKind::Infer
+                } else {
+                    TyKind::Path(path)
+                }
+            }
             t => Err(p.error(Unexpected(t), P))?,
         };
 

compiler/cl-repl/examples/yaml.rs

@@ -637,6 +637,7 @@ pub mod yamlify {
             match self {
                 TyKind::Never => y.value("Never"),
                 TyKind::Empty => y.value("Empty"),
+                TyKind::Infer => y.value("_"),
                 TyKind::Path(t) => y.yaml(t),
                 TyKind::Tuple(t) => y.yaml(t),
                 TyKind::Ref(t) => y.yaml(t),

compiler/cl-typeck/src/type_expression.rs

@@ -42,6 +42,10 @@ impl TypeExpression for TyKind {
         match self {
             TyKind::Never => Ok(table.anon_type(TypeKind::Never)),
             TyKind::Empty => Ok(table.anon_type(TypeKind::Empty)),
+            TyKind::Infer => {
+                eprintln!("TODO: Introduce type variables");
+                Err(Error::BadPath { parent: node, path: vec![PathPart::Ident("_".into())] })
+            }
             TyKind::Path(p) => p.evaluate(table, node),
             TyKind::Array(a) => a.evaluate(table, node),
             TyKind::Slice(s) => s.evaluate(table, node),