Am 08/07/2016 um 05:18 PM schrieb Kim-Ee Yeoh:
Have you heard of Djinn?
https://hackage.haskell.org/package/djinn
If you punch in the signature of the combine function you're looking for (rewritten more usefully in Kleisli composition form):
(Int -> (Integer->r) -> r) -> (Integer -> (String -> r) -> r) -> (Int -> (String -> r) -> r)
Thanks for pointing out Djinn, but I want to understand. And there are a number of things I don't understand. Maybe you can help me out: (1) what is the "more useful Kleisli composition" and what would be "less useful" ? (2) I was hoping my experiments would eventually make the Cont monad appear and I originally even named my combinator 'bind' instead of 'combine'. My hope was fueled by the observation that combine a f g = f a g works with f substitued with f1 :: Int -> (Integer->r) -> r and g substitued with f2 :: Integer -> (String -> r) -> r As a next step I would have wrapped (b->r) -> r in a newtype C r b and my functions f1 and f2 would have had the types f1 :: Int -> C r Integer f2 :: Integer -> C r String Now my 'combine' function seems to be different from 'bind' (>>=). It also just too simple to be true. Somwhere I am making a fundamental mistake, but I cannot quite see it.