Cont.hs

{-# LANGUAGE RankNTypes #-}

module Cont where 

import Data.Coerce
import Data.Function
import Control.Applicative
import Control.Monad

newtype Cont a = Cont { runCont :: forall r. (a -> r) -> r }

cont :: a -> Cont a
cont a = Cont ($ a)

instance Functor Cont where
  fmap = liftM

instance Applicative Cont where
  pure = cont
  liftA2 = liftM2
  (*>) = (>>)
  (<*) = flip (>>)

instance Monad Cont where
  (>>=) = runCont