Haskell with Emacs is awesome! There's a few modes available to have a powerful IDE.
I don't remember which ones as xmonad + yi (or vi) is enough for me now.
My main reason of change is because emacs was getting too slow and buggy. After trying a few hacks in 'init.el' and co, it was getting worse... Suddendly Yi!
As I code only in haskell, it's perfect fun for me.
Now, maybe a good way to start is using/practicing their Vimgolf client. [0]
In emacs, as I didn't use any others modes (except haskell-mode ...), I don't need their wonderful package managers any more.