fix: iterator bugs

crates/erg_compiler/context/initialize/classes.rs

@@ -1761,7 +1761,10 @@ impl Context {
         let mut enumerate = Self::builtin_poly_class(ENUMERATE, vec![PS::t_nd(TY_T)], 2);
         enumerate.register_superclass(Obj, &obj);
         enumerate
-            .register_marker_trait(self, poly(ITERABLE, vec![ty_tp(T.clone())]))
+            .register_marker_trait(
+                self,
+                poly(ITERABLE, vec![ty_tp(tuple_t(vec![Nat, T.clone()]))]),
+            )
             .unwrap();
         enumerate
             .register_marker_trait(self, poly(OUTPUT, vec![ty_tp(T.clone())]))

crates/erg_compiler/context/initialize/funcs.rs

@@ -77,7 +77,7 @@ impl Context {
         .quantify();
         let t_filter = nd_func(
             vec![
-                kw(KW_FUNC, nd_func(vec![anon(T.clone())], None, T.clone())),
+                kw(KW_FUNC, nd_func(vec![anon(T.clone())], None, Bool)),
                 kw(KW_ITERABLE, poly(ITERABLE, vec![ty_tp(T.clone())])),
             ],
             None,

tests/should_ok/iterator.er

@@ -0,0 +1,8 @@
+for! enumerate(0..3), ((i, j),) =>
+    assert i == j
+for! zip(0..3, 0..3), ((i, j),) =>
+    assert i == j
+for! filter(x -> x > 1, 0..3), i =>
+    assert i > 1
+for! map(x -> "\{x}", [1, 2, 3]), s =>
+    assert str(s) == s

tests/test.rs

@@ -394,6 +394,11 @@ fn exec_invalid_param() -> Result<(), ()> {
     expect_failure("tests/should_err/invalid_param.er", 0, 3)
 }
 
+#[test]
+fn exec_iterator() -> Result<(), ()> {
+    expect_success("tests/should_ok/iterator.er", 0)
+}
+
 #[test]
 fn exec_move_check() -> Result<(), ()> {
     expect_failure("examples/move_check.er", 1, 1)