2008/10/1 Cetin Sert <[EMAIL PROTECTED]>: > warn :: String → IO Int > warn = return 1 << putStrLn -- causes an error > -- = \msg → return 1 << putStrLn msg -- works just fine > -- = \msg → putStrLn msg >> return 1 -- works just fine > > (<<) :: Monad m ⇒ m b → m a → m b > b << a = a >>= \_ → b > > Why do I get this compile-time error?? How can one define << ?
While this isn't directly what you're doing, you might be interested in the Kleisli composition operators in Control.Monad: (>=>) :: (Monad m) => (a -> m b) -> (b -> m c) -> (a -> m c) (<=<) :: (Mnoad m) => (b -> m c) -> (a -> m b) -> (a -> m c) Luke _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
