gistfile1.hs

import Prelude hiding ((++))
import qualified Prelude as P

class ListLike a where
  (++) :: a b -> a b -> a b
  (<:) :: b -> a b -> a b
  (>:) :: a b -> b -> a b
  nil :: a b


newtype L a = L ([a] -> [a])
unL :: L a -> [a] -> [a]
unL (L f) = f

toList :: L a -> [a]
toList f = (unL f) [ ]

instance ListLike [] where
  (++) = (P.++)
  (<:) = (:)
  (>:) xs x = xs ++ [x]
  nil = []

instance ListLike L where
  (++) f g = L (unL f . unL g)
  (<:) x f = L ((x:) . unL f)
  (>:) f x = L (unL f . (x:))
  nil = L id


reverse'' :: [a] -> L a
reverse'' [] = nil
reverse'' (x:xs) = (reverse'' xs) >: x