dunai-0.1.1.0: src/Data/MonadicStreamFunction/ArrowChoice.hs

{-# OPTIONS_GHC -fno-warn-orphans #-}
module Data.MonadicStreamFunction.ArrowChoice where

import Control.Arrow

import Data.MonadicStreamFunction.Core

instance Monad m => ArrowChoice (MSF m) where
  left sf = MSF f
    where
      f (Left a) = do (b, sf') <- unMSF sf a
                      return (Left b, left sf')
      f (Right c) = return (Right c, left sf)