Editing haskell code is a pain in the ass.
There isn't a good IDE for haskell which can help you learn all the possibilities of the language by advising better solutions to a specific problem.
On the other side if you choose to use a text editor (Sublime) you'll write several lines of code just to get hilarious compiler errors like:
Could not deduce (b ~ a) from the context (Eq a, Eq b)
Luckily github released its new, revolutionary text editor last week:
The solution###**[Atom Text Editor](https://atom.io/) + [Haskell IDE package](https://atom.io/packages/ide-haskell)**
Just download the Editor from their website and install the packages following packages using
File > Settings > + Install
The fast way:
$ apm install language-haskell haskell-ghc-mod ide-haskell autocomplete-haskell