[mightybyte]

I would do it something like this:

    top xs = map fst $ sortBy (compare `on` Down . snd) $
        M.toList $ foldr (\x -> M.insertWith (+) x 1) mempty xs

This has the type `top :: Ord a => [a] -> [a]`. You might object that I didn't include your k parameter. Because Haskell is a lazy language, I can get your behavior very simply by doing `take n . top` and it will lazily only calculate the first n values. This gives you more abstractive power and lets you write more composable code.

[chubot]

Yeah, so this sort of proves my point :)

I don't begrudge anyone if they want to use Haskell or OCaml for everything.

But personally I am interested in using ML-like languages for language engineering and not general purpose programming (maybe Rust could change that, but I'm not convinced). I program in 5+ different languages regularly so I've dealt with all the friction involved, mainly by explicitly designing systems as heterogeneous collections of Unix processes.

[mightybyte]

Hmmm, I'm not sure what you're saying. What point does it prove? I've been using Haskell for general purpose programming for five years now and I've found it to be exceptionally well-suited.