Next LS

The language server for Elixir that just works. 😎

Still in heavy development, currently supporting the following features:

• Compiler Diagnostics
• Code Formatting
• Workspace Symbols
• Document Symbols
• Go To Definition
• Workspace Folders
• Find References
• Extensions
  • Credo
• Hover
• Completions †‡

† - denotes an experimental feature, which can be toggled on/off.

‡ - denotes a partially implemented feature.

Supported Elixir Versions

Currently it supports 1.13 and newer, but this could be lowered potentially.

Editor Support

• Neovim: elixir-tools.nvim
• VSCode: elixir-tools.vscode
• Emacs - eglot

  (require 'eglot)
  
  (add-to-list 'exec-path "path/to/next-ls/bin/")
  
  (with-eval-after-load 'eglot
    (add-to-list 'eglot-server-programs
                 `((elixir-ts-mode heex-ts-mode elixir-mode) .
                   ("nextls" "--stdio=true"))))
  
  (add-hook 'elixir-mode-hook 'eglot-ensure)
  (add-hook 'elixir-ts-mode-hook 'eglot-ensure)
  (add-hook 'heex-ts-mode-hook 'eglot-ensure)

• Doom Emacs - eglot

  1. Install nextls somewhere on your PATH

  2. Enable lsp with eglot in $DOOMDIR/init.el

     - ;; lsp
     + (lsp +eglot)

  3. Enable the Elixir layer with lsp in $DOOMDIR/init.el

     - ;; elixir
     + (elixir +lsp)

  4. Configure the eglot client in $DOOMDIR/config.el

     (set-eglot-client! 'elixir-mode '("nextls" "--stdio"))

• Helix

  Add the following config to your ~/.config/helix/languages.toml.

  [[language]]
  name = "elixir"
  scope = "source.elixir"
  language-server = { command = "path/to/next-ls", args = ["--stdio=true"] }

  If you are using the latest git version of helix use this:

  [[language]]
  name = "elixir"
  scope = "source.elixir"
  language-servers = ["nextls"]
  
  [language-server.nextls]
  command = "path/to/next-ls"
  args = ["--stdio=true"]

• Zed

  Zed

  Add the following settings (tested with Zed Preview v0.106.2):

  {
    "elixir": {
      "lsp": "next_ls"
    }
  }

  If you would like to set initialization options, for example to enable an experimental feature, you can add the following to your settings.json file.

  Note the different between snake case and kebab case between the third and sixth lines.

  {
    "elixir": {
      "lsp": "next_ls"
    },
    "lsp": {
       "next-ls": {
           "initialization_options": {
               "experimental": {
                 "completions": {
                   "enable": true
                 }
               }
           }
       }
    }
  }

• Vim - prabirshrestha/vim-lsp

  vim-lsp

  Install Next LS somewhere on your PATH, or instead use an absolute path to the Next LS executable.

  if executable('nextls')
      au User lsp_setup call lsp#register_server({
          \ 'name': 'next_ls',
          \ 'cmd': ["nextls", "--stdio"],
          \ 'root_uri':{server_info->lsp#utils#path_to_uri(
          \	lsp#utils#find_nearest_parent_file_directory(
          \		lsp#utils#get_buffer_path(),
          \		['mix.exs']
          \	))},
          \ 'allowlist': ['elixir'],
          \ })
  endif

• Vim - yegappan/lsp

  yegappan/lsp - requires Vim 9

  Install Next LS somewhere on your PATH, or instead use an absolute path to the Next LS executable.

  let lspServers = [#{
  	\	  name: 'next_ls',
  	\	  filetype: ['elixir'],
  	\	  path: 'nextls',
  	\	  args: ['--stdio'],
    \   rootSearchFiles: ['mix.exs']
  	\ }]
  autocmd VimEnter * call LspAddServer(lspServers)

• Vim - ALE

  Valid once dense-analysis/ale#4626 is merged.

  ALE

  Install Next LS somewhere on your PATH, or instead use an absolute path to the Next LS executable.

  let g:ale_elixir_next_ls_executable = 'path/to/nextls' " optional, if you want to change the executable that is used
  let g:ale_linters = {'elixir': ['next_ls']}

Installation

Editor Extensions

The preferred way to use Next LS is through one of the supported editor extensions.

The extension will automatically install the latest version of Next LS and will be kept up to date automatically.

Homebrew

brew install elixir-tools/tap/next-ls

Nix

nix profile install github:elixir-tools/next-ls

GitHub Releases

If you need to install Next LS on it's own, you can download the appropriate executable from our GitHub Releases.

These executables are created with Burrito and are completely standalone, except you'll still need Elixir and OTP installed in order for it to start a runtime for your application code.

Development

If you are making changes to Next LS and want to test them locally you can run bin/start --port 9000 to start the language server (port 9000 is just an example, you can use any port that you want as long as it is not being used already).

Then you can configure your editor to connect to Next LS using that port.

elixir-tools.nvim

{
  nextls = {enable = true, port = 9000}
}

Visual Studio Code

{
  "elixir-tools.nextLS.adapter": "tcp",
  "elixir-tools.nextLS.port": 9000
}

Note

Next LS creates an .elixir-tools hidden directory in your project, but it will be automatically ignored by git.

Troubleshooting

1. Is epmd running?

Linux/Mac:

pgrep -fl epmd

If epmd is not running, you might need to start it or ensure it starts automatically with your system. You can do this by running epmd -daemon.

2. Ensure glibc version is at least 2.34

Linux:

ldd --version

This will show the glibc version at the top. Ensure it's 2.34 or higher.

Mac:

macOS doesn't use glibc; it uses the Darwin C Library. Hence, this step is not applicable.

Windows:

Windows does not use glibc. If you're using a subsystem or tool that needs it, ensure it's updated.

3. Open Visual Studio Code from the terminal

To ensure that elixir is in your PATH, open Visual Studio Code from the terminal using the command-line tools.

4. Does it work in TCP mode?

All Platforms:

Start the language server in TCP mode and connect to it with your editor, as described above.

Both extensions install the Next LS executable to ~/.cache/elixir-tools/nextls/bin/nextls, so you can start the server with ~/.cache/elixir-tools/nextls/bin/nextls --port 9000.

5. Firewall Interference

Sometimes, the firewall can interfere with epmd and each Erlang node's ability to cluster. If you face connection issues, you might try turning off the firewall temporarily to see if it resolves the issue.

This is usually a problem on macOS, as you should see a popup asking if beam and epmd can accept incoming connections (which you should click "yes").

In future version, we plan to sign and notarize the darwin binaries, which should avoid this popups and make this a non-issue.