convertType (HsFunTy NOEXTP ty1 ty2) =
  Arrow <$> convertLType ty1 <*> convertLType ty2
convertType (HsFunTy NOEXTP ty1 ty2) =
  Arrow <$> convertLType ty1 <*> convertLType ty2
convertType (HsFunTy NOEXTP ty1 ty2) =
  Arrow <$> convertLType ty1 <*> convertLType ty2