isTFHeaded ty | (TyConApp tc args) <- ty
              , isTypeFamilyTyCon tc
              = tyConArity tc == length args
isTFHeaded ty | (TyConApp tc args) <- ty
              , isTypeFamilyTyCon tc
              = tyConArity tc == length args
isTFHeaded ty | (TyConApp tc args) <- ty
              , isTypeFamilyTyCon tc
              = tyConArity tc == length args