diff --git a/src/front/check.ts b/src/front/check.ts
index 0831f2b..97db688 100644
--- a/src/front/check.ts
+++ b/src/front/check.ts
@@ -470,6 +470,10 @@ class TypeChecker {
                 const callableTy = calleeTy.callableTy();
 
                 if (callableTy.kind.generics !== null) {
+                    ((() => {
+                        throw new Error("generics not implemented");
+                    }) as () => void)();
+
                     let generics: Ty[];
                     if (k.generics) {
                         generics = k.generics.map((ty) => this.ty(ty));