More golf...

Update - I submitted it after all, and as a message to self, I really should write emails for public distribution in a separate editor and proof read them properly before pressing send.

Old post begins...

Currently on haskell-beginners there's a thread 'list monad question' with more golf practice. I'd go further than the current pointfree version, but decided not to submit after typing it up. I'm not sure of the merits of posting incomprehensible code on a beginners list.

-- combinations :: Int -> [a] -> [[a]]
-- combinations = (foldr ((. (. (:)) . flip map) . (>>=)) [[]]  .) . replicate

-- The pointfree version can be golfed even further if you consider
-- some useful combinators not found in the standard libraries

combinations :: Int -> [a] -> [[a]]
combinations = foldr (<:>) [[]] `oo` replicate

-- | Applicative 'cons'.

(<:>) :: Applicative f => f a -> f [a] -> f [a]
(<:>) a b = (:) <$> a <*> b



-- | Compose an arity 1 function with an arity 2 function.
--
-- I call this combinator 'specs' (aka glasses) due to its infix
-- appearance `oo` 

oo :: (c -> d) -> (a -> b -> c) -> a -> b -> d
oo f g = (f .) . g