+
+typeArity :: Type -> Arity
+-- How many value arrows are visible in the type?
+-- We look through foralls, but not through newtypes, dictionaries etc
+typeArity ty | Just ty' <- coreView ty = typeArity ty'
+typeArity (FunTy _ ty) = 1 + typeArity ty
+typeArity (ForAllTy _ ty) = typeArity ty
+typeArity _ = 0