Developing with Elixir in Vim

Using (Neo)Vim is surprisingly enjoyable after the initial hurdle.

Language support for Elixir also works fine in Vim.

Plugins

I use minpac as my package manager. VimCasts has a good introduction video on minpac if you're interested.

Add these plugins to your ~/.vimrc:

• elixir-editors/vim-elixir
• optional: tpope/endwise for automatically adding end after def, do, etc.
• optional: dense-analysis/ale for fixing and linting files

Configuration:

" in `.vimrc` or `~/.config/nvim/init.vim`
syntax on
filetype plugin indent on

set laststatus=2
set wildmenu

Elixir Language Server

You need the Elixir Language Server as a backend/integration tool.

Either head over to the original elixir-ls (slow development at the moment) or the more current fork elixir-lsp elixir-ls fork.

You need to clone the repository.

$ git clone [e-mail]:elixir-lsp/elixir-ls.git
$ cd elixir-ls
$ mix deps.get
$ mix compile
$ MIX_ENV=prod mix elixir_ls.release

This creates a folder release which includes an executable, for example release/language_server.sh (.bat for Windows).

You need the path to that file for ALE support.

ALE

ALE acts as the client for the Elixir Language Server. Setup for ALE also needs to go into your vim settings (~/.vimrc):

" in `.vimrc` or `~/.config/nvim/init.vim`

let g:ale_linters = {
\   'elixir': ['elixir-ls'],
\}

let g:ale_fixers = {
\   'elixir': ['mix_format'],
\}

You also have to tell ALE where the language server is:

" in `.vimrc` or `~/.config/nvim/init.vim`

let g:ale_elixir_elixir_ls_release='~/<PATH-TO-YOUR-RELEASE>'

Only specify the path, not the file itself (language_server.sh or language_server.bat).

Now, you can use the command :ALEFix in Vim to fix your files.

I chose the following config options:

" in `.vimrc` or `~/.config/nvim/init.vim`

let g:ale_completion_enabled = 1
let g:ale_sign_error = '✘'
let g:ale_sign_warning = '⚠'
let g:ale_lint_on_enter = 0
let g:ale_lint_on_text_changed = 'never'
highlight ALEErrorSign ctermbg=NONE ctermfg=red
highlight ALEWarningSign ctermbg=NONE ctermfg=yellow
let g:ale_linters_explicit = 1
let g:ale_lint_on_save = 1
let g:ale_fix_on_save = 1

noremap <Leader>ad :ALEGoToDefinition<CR>
nnoremap <leader>af :ALEFix<cr>
noremap <Leader>ar :ALEFindReferences<CR>

"Move between linting errors
nnoremap ]r :ALENextWrap<CR>
nnoremap [r :ALEPreviousWrap<CR>

Better Language Client Support

ALE is great for linting and fixing files, but it can make VIM slow.

Alternatively, you can use a dedicated language server plugin, for example LanguageClient-neovim (works for Vim8 and NeoVim).

You can find a guide here.

Further Reading

• How to use Elixir LS with Vim by Mitchell Hanberg
• Emacs - Elixir Setup Configuration Wiki
• How I configure Vim to work with Elixir without much clutter by Hauleth - and forum post