How to install Ormolu in Vim and format when saving?

Beau Barker, May 8, 2022. Updated Sep 13, 2025. ✎

Install Ormolu:

ghcup install cabal latest
cabal install ormolu

Ensure the created binary is in your $PATH.

Install Vim plugin:

git -C ~/.vim/pack/plugins/start clone https://github.com/sdiehl/vim-ormolu

Add autocmd to ~/.vimrc:

autocmd BufWritePre *.hs :call RunOrmolu()