scalafmt in Neovim with scalafmt-native

I previously wrote a post on setting up scalafmt to autoformat Scala code in Neovim. That guide used nailgun to help keep scalafmt fast to run, however my setup was a bit flaky and frequently broke. Fortunately, scalafmt now provides native binaries compiled with GraalVm, which starts up and runs quickly enough that we don’t need to use the more complex nailgun setup. This blog post provides an updated guide on using scalafmt in Neovim with scalafmt-native.

1. Install scalafmt-native

Follow the scalafmt docs to install scalafmt-native.

curl | \

scalafmt-native should then be available in the terminal. Test it with:

scalafmt-native --help

2. Configure Neovim

With scalafmt-native installed, configure Neovim to automatically apply scalafmt formatting to our Scala source files.

Install neoformat with your favourite plugin manager. For example, with vim-plug, add to ~/.config/nvim/init.vim:

Plug 'sbdchd/neoformat'

then reopen Neovim and run :PlugInstall.

In ~/.config/nvim/init.vim, configure neoformat to use scalafmt-native with:

let g:neoformat_scala_scalafmt = {
        \ 'exe': 'scalafmt-native',
        \ 'args': ['--stdin'],
        \ 'stdin': 1,
        \ }

Finally, to configure Neovim to automatically apply formatting to Scala files on save, add the following line to ~/.config/nvim/init.vim:

autocmd BufWritePre *.{scala,sbt} Neoformat