helper: Fix applying substitution with shadowed type variable names i…

…n type quantifiers
domdomegg · Aug 20, 2024 · 26af0e9 · 26af0e9
1 parent 53fc543
commit 26af0e9
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/helper.ts b/helper.ts
@@ -40,7 +40,8 @@ function apply(s: Substitution, value: MonoType | PolyType | Context): MonoType
   }
 
   if (value.type === "ty-quantifier") {
-    return { ...value, sigma: apply(s, value.sigma) };
+    const substitutionWithoutQuantifier = makeSubstitution(Object.fromEntries(Object.entries(s.raw).filter(([k, v]) => k !== value.a)));
+    return { ...value, sigma: apply(substitutionWithoutQuantifier, value.sigma) };
   }
 
   throw new Error('Unknown argument passed to substitution')