{-# LANGUAGE
  TypeFamilies,
  UndecidableInstances
  #-}
module Types.Data.List.Ops
    ( App
    , App2
    , App3
    , App4
    , App5

    , Map
    , Foldl
    )
    where

import Types.Data.List


type family App  f a
type family App2 f a b
type family App3 f a b c
type family App4 f a b c d
type family App5 f a b c d e

type family   Map f l
type instance Map f Null        = Null
type instance Map f (Cons x xs) = Cons (App f x) (Map f xs)

type family   Foldl f z l
type instance Foldl f z Null        = z
type instance Foldl f z (Cons x xs) = Foldl f (App2 f z x) xs