Andrew Coppin
The other day, I accidentally came up with this:
|{-# LANGUAGE RankNTypes #-}
type Either x y= forall r. (x -> r) -> (y -> r) -> r
left :: x -> Either x y left x f g= f x
right :: y -> Either x y right y f g= g y
This is one example; it seems that just about any algebraic type can be encoded this way. I presume that somebody else has thought of this before. Does it have a name?
You may want to have a look at my contstuff library, which implements all the usual monads in CPS: http://hackage.haskell.org/package/contstuff This is just the style you implemented Either in, but slightly more general and with an explicit result type parameter: newtype EitherT r e m a = EitherT { getEitherT :: (a -> m r) -> (e -> m r) -> m r } Greets, Ertugrul -- nightmare = unsafePerformIO (getWrongWife >>= sex) http://ertes.de/