module Control.Arrow.ArrowKleisli where
import Control.Arrow
import Control.Category
import Control.Monad.Trans
import Prelude hiding ((.), id)
class (Monad m, Arrow arr) => ArrowKleisli m arr | arr -> m where
arrM :: (a -> m b) -> a `arr` b
instance Monad m => ArrowKleisli m (Kleisli m) where
arrM f = Kleisli f
constM :: ArrowKleisli m arr => m b -> a `arr` b
constM a = arrM (const a)
effect :: ArrowKleisli m arr => m () -> a `arr` a
effect a = arrM (\b -> a >> return b)
arrIO :: (MonadIO m, ArrowKleisli m arr) => (a -> IO b) -> a `arr` b
arrIO f = arrM (liftIO . f)