module Control.Monad.Composition where
import Control.Monad
import Control.Functor.Composition.Class
import Control.Functor.Extras
import Control.Functor.Pointed
import Control.Functor.Pointed.Composition
postJoin :: (Monad m, PostFold m f) => m (f (m (f a))) -> m (f a)
postJoin = join . liftM postFold
instance (Monad m, Pointed f, PostFold m f) => Monad (PostCompF m f) where
return = compose . return . point
m >>= k = undefined
preJoin :: (Monad m, Functor f, PreFold f m) => f (m (f (m a))) -> f (m a)
preJoin = fmap join . preFold
instance (Pointed f, Monad m, PreFold f m) => Monad (PreCompF f m) where
return = compose . point . return
m >>= k = undefined
instance (Monad m, Monad n, Distributes m n) => Monad (DistCompF m n) where
return = compose . return . return
m >>= k = undefined