[fine] Fix list variable binding

fine/src/parser.rs

@@ -139,6 +139,7 @@ pub enum TreeKind {
     Identifier,
     IfStatement,
     IsExpression,
+    IteratorVariable,
     LetStatement,
     ListConstructor,
     ListConstructorElement,
@@ -889,10 +890,7 @@ fn statement_for(p: &mut CParser) {
     let m = p.start();
 
     p.expect_start(TokenKind::For);
-    p.expect(
-        TokenKind::Identifier,
-        "expected an identifier for the loop variable",
-    );
+    iterator_variable(p);
     p.expect(TokenKind::In, "expect an 'in' after the loop variable");
     if p.at_any(EXPRESSION_FIRST) {
         expression(p);
@@ -904,6 +902,17 @@ fn statement_for(p: &mut CParser) {
     p.end(m, TreeKind::ForStatement);
 }
 
+fn iterator_variable(p: &mut CParser) {
+    let m = p.start();
+
+    p.expect(
+        TokenKind::Identifier,
+        "expected an identifier for the iterator variable",
+    );
+
+    p.end(m, TreeKind::IteratorVariable);
+}
+
 fn statement_expression(p: &mut CParser) {
     let m = p.start();
 

fine/src/semantics.rs

@@ -908,31 +908,19 @@ impl<'a> Semantics<'a> {
         EnvironmentRef::new(environment)
     }
 
-    fn environment_of_for(&self, parent: EnvironmentRef, _tree: &Tree) -> EnvironmentRef {
-        // let Some(id) = tree.nth_token(1) else {
-        //     return parent;
-        // };
+    fn environment_of_for(&self, parent: EnvironmentRef, tree: &Tree) -> EnvironmentRef {
+        let Some(it) = tree.nth_tree(1) else {
+            return parent;
+        };
 
-        // let Some(enumerable) = tree.nth_tree(3) else {
-        //     return parent;
-        // };
+        let iterator = &self.syntax_tree[it];
+        let Some(id) = iterator.nth_token(0) else {
+            return parent;
+        };
 
-        // let item_type = match self.type_of(enumerable) {
-        //     Type::Error => Type::Error,
-        //     Type::List(x) => (&*x).clone(),
-        //     _ => {
-        //         self.report_error_tree_ref(enumerable, "this expression is not enumerable");
-        //         Type::Error
-        //     }
-        // };
-
-        // TODO: This is broken, need a sub-tree to point the decl at that
-        // has the right type.
-        //
-        // let mut environment = Environment::new(Some(parent), Location::Local);
-        // environment.insert(id, item_type);
-        // EnvironmentRef::new(environment)
-        parent
+        let mut environment = Environment::new(Some(parent), Location::Local);
+        environment.insert(id, it);
+        EnvironmentRef::new(environment)
     }
 
     fn environment_of_is_expression(&self, parent: EnvironmentRef, tree: &Tree) -> EnvironmentRef {
@@ -1277,6 +1265,7 @@ impl<'a> Semantics<'a> {
             TreeKind::Identifier => self.type_of_identifier(t, tree),
             TreeKind::IfStatement => self.type_of_if_statement(tree),
             TreeKind::IsExpression => Some(Type::Bool),
+            TreeKind::IteratorVariable => self.type_of_iterator_variable(tree),
             TreeKind::LetStatement => Some(Type::Nothing),
             TreeKind::ListConstructor => self.type_of_list_constructor(t, tree),
             TreeKind::ListConstructorElement => self.type_of_list_constructor_element(tree),
@@ -1938,6 +1927,24 @@ impl<'a> Semantics<'a> {
         }
     }
 
+    fn type_of_iterator_variable(&self, tree: &Tree) -> Option<Type> {
+        assert_eq!(tree.kind, TreeKind::IteratorVariable);
+        let parent = &self.syntax_tree[tree.parent?];
+        assert_eq!(parent.kind, TreeKind::ForStatement);
+
+        let enumerable = parent.nth_tree(3)?;
+        let item_type = match self.type_of(enumerable) {
+            Type::Error => Type::Error,
+            Type::List(x) => (&*x).clone(),
+            _ => {
+                self.report_error_tree_ref(enumerable, "this expression is not enumerable");
+                Type::Error
+            }
+        };
+
+        Some(item_type)
+    }
+
     fn type_of_list_constructor(&self, t: TreeRef, tree: &Tree) -> Option<Type> {
         assert_eq!(tree.kind, TreeKind::ListConstructor);
         let mut element_type = None;
@@ -2346,7 +2353,9 @@ pub fn check(s: &Semantics) {
             TreeKind::ListConstructorElement => {
                 let _ = s.type_of(t);
             }
+
             TreeKind::ForStatement => check_for_statement(s, t),
+            TreeKind::IteratorVariable => {}
 
             TreeKind::ClassDecl => check_class_declaration(s, tree),
             TreeKind::FieldDecl => {}

fine/tests/expression/lists.fine

@@ -13,4 +13,4 @@ fun test() -> f64 {
 
 // @ignore WIP
 // @no-errors
-// @type: 88 list<f64>
+// @type: 155 list<f64>