Syntax Highlighting and Indentation for Haskell and Cabal

I was unhappy with the Haskell scripts that are shipped with vim, therefore I decided to make my own based on idris-vim.

I hope you find this useful.

Features

• Covers a broader spectrum of keywords
• Highlighting for new features like type families, pattern synonyms, arrow syntax, recursive do, role annotations, QuasiQuotation
• More contextual highlighting (e.g. highlight 'as' or 'family' only in appropriate places)
• Smarter indentation
• Better Cabal support

Installation

I recommend using Pathogen for installation. Simply clone this repo into your ~/.vim/bundle directory and you are ready to go.

cd ~/.vim/bundle
git clone https://github.com/neovimhaskell/haskell-vim.git

Be sure that the following lines are in your .vimrc

syntax on
filetype plugin indent on

Manual Installation

Copy content into your ~/.vim directory.

Configuration

Features

To enable the features you would like to use, just add the according line to your .vimrc.

let g:haskell_enable_quantification = 1   " to enable highlighting of `forall`
let g:haskell_enable_recursivedo = 1      " to enable highlighting of `mdo` and `rec`
let g:haskell_enable_arrowsyntax = 1      " to enable highlighting of `proc`
let g:haskell_enable_pattern_synonyms = 1 " to enable highlighting of `pattern`
let g:haskell_enable_typeroles = 1        " to enable highlighting of type roles
let g:haskell_enable_static_pointers = 1  " to enable highlighting of `static`

Highlighting

haskell-vim has an opinionated highlighting. If you do not like that you can switch to a more traditional mode by setting g:haskell_classic_highlighting to 1.

Indentation

To configure indentation in haskell-vim you can use the following variables to change indentation depth, just add the according line to your .vimrc.

Haskell

• let g:haskell_indent_if = 3

    if bool
    >>>then ...
    >>>else ...
  

• let g:haskell_indent_case = 2

    case xs of
    >>[]     -> ...
    >>(y:ys) -> ...
  

• let g:haskell_indent_let = 4

    let x = 0 in
    >>>>x
  

• let g:haskell_indent_where = 6

    where f :: Int -> Int
    >>>>>>f x = x
  

• let g:haskell_indent_do = 3

    do x <- a
    >>>y <- b
  

• let g:haskell_indent_in = 1

    let x = 1
    >in x
  

• let g:haskell_indent_guard = 2

    f x y
    >>|
  

Cabal

• let g:cabal_indent_section = 2 (limited to max. 4 spaces)

   executable name
   >>main-is:             Main.hs