Fix: polymorphic and concrete numeral types are now distinguished

before: > foo : (Foo String Int a) > add_one : forall a. (Maybe I32 -> Maybe I32 can a) after: > foo : (Foo String (Int a)) > add_one : forall a. (Maybe I32 -> Maybe I32 can a) -- No change for concrete types refs: #203 (comment)
jfecher · Nov 11, 2024 · afe8213 · afe8213
1 parent fc88982
commit afe8213
Showing 1 changed file with 18 additions and 2 deletions.
diff --git a/src/types/mod.rs b/src/types/mod.rs
@@ -250,8 +250,24 @@ impl Type {
                 TypeBinding::Unbound(..) => TypePriority::MAX,
             },
             Function(_) => TypePriority::FUN,
-            TypeApplication(ctor, _) if ctor.is_polymorphic_int_type() => TypePriority::MAX,
-            TypeApplication(ctor, _) if ctor.is_polymorphic_float_type() => TypePriority::MAX,
+            TypeApplication(ctor, args) if ctor.is_polymorphic_int_type() => {
+                if matches!(cache.follow_typebindings_shallow(&args[0]), Type::TypeVariable(_)) {
+                    // type variable is unbound variable
+                    TypePriority::APP
+                } else {
+                    // type variable is bound (polymorphic int)
+                    TypePriority::MAX
+                }
+            },
+            TypeApplication(ctor, args) if ctor.is_polymorphic_float_type() => {
+                if matches!(cache.follow_typebindings_shallow(&args[0]), Type::TypeVariable(_)) {
+                    // type variable is unbound variable
+                    TypePriority::APP
+                } else {
+                    // type variable is bound (polymorphic float)
+                    TypePriority::MAX
+                }
+            },
             TypeApplication(ctor, _) => {
                 if ctor.is_pair_type() {
                     TypePriority::PAIR