{-# LANGUAGE
  RankNTypes
  #-}
module Control.Monad.Trans.AnyCont where

import Control.Applicative
import Control.Monad.Cont

newtype AnyContT m a = AnyContT { unAnyContT :: forall r . ContT r m a }

instance Functor (AnyContT m) where
  fmap f p = AnyContT $ fmap f . unAnyContT $ p

instance Applicative (AnyContT m) where
  pure a = AnyContT $ pure a
  f <*> v = AnyContT $ unAnyContT f <*> unAnyContT v

instance Monad m => Monad (AnyContT m) where
  AnyContT f >>= k = AnyContT $ f >>= unAnyContT . k
  return a = AnyContT $ return a
  fail s = AnyContT (ContT (\_ -> fail s))
  
instance MonadIO m => MonadIO (AnyContT m) where
  liftIO = lift . liftIO

instance MonadTrans AnyContT where
  lift ma = AnyContT (lift ma)

runAnyContT :: AnyContT m a -> (forall r . (a -> m r) -> m r)
runAnyContT = runContT . unAnyContT
anyContT :: (forall r . (a -> m r) -> m r) -> AnyContT m a
anyContT f = AnyContT (ContT f)

withAnyContT :: (forall r . (b -> m r) -> (a -> m r)) -> AnyContT m a -> AnyContT m b
withAnyContT f m = anyContT $ runAnyContT m . f

mapAnyContT :: (forall r . m r -> m r) -> AnyContT m a -> AnyContT m a
mapAnyContT f m = anyContT $ f . runAnyContT m