Official Haskell omni completion plugin distributed in Vim's runtime.
If your Vim's runtime is up to date you should already have it, if not, you can install it as a normal plugin.
Compatible with Vundle, Vim-plug, Pathogen, etc.
If you install it as an external plugin, you might need to set the omnifunc
with setlocal omnifunc=haskellcomplete#Complete.
Or add an auto command to your .vimrc file:
augroup ft_haskell
au!
au FileType haskell setlocal omnifunc=haskellcomplete#Complete
augroup ENDUse normal omni completion mechanisms.
:h i_CTRL-X_CTRL-O- GHC language extensions pragma
{-# LANGUAGE <complete here> #-}- GHC flags pragma
{-# OPTIONS_GHC <complete here> #-}- Core packages module names
import <complete here>