Improve Haskell Syntax Highlighting.

[YellowOnion]

Haskell Syntax highlighting seems dull.

Currently all of these are one colour: functions/variables (definitions and use), brackets, types.
As well as operators and keywords are also the same colour.

There only seems to be a total of 5 colours on screen

Haskell's "lack" of liveliness is probably related to the fact that functions and variables are the same thing syntactically.

Here is a comparison between Spacemacs and Oni.

Also, Oni reminds me of when I used gVim, so it could be an upstream issue.

[oni-bot]

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[badosu]

Are you using any Haskell syntax highlighting plugin for vim or depending solely on Oni's default one?

[akinsho]

Another point is I'm pretty sure Oni isn't bundled with a textmate grammar for haskell which would provide syntax highlighting as well -> another good first issues for anyone interested would essentially be copy pasting a file into the extensions/haskell and adding the path in onis default config's dir like was done in #2539