nil: NIx Language server

An incremental analysis assistant for writing in Nix.

See release notes for change log between tagged unstable versions.

See docs/features.md for an incomplete list of notable features currently implemented or planned.

See docs/configuration.md for all tunable configuration options.

Installation

This program is already included in NixOS/nixpkgs under attribute nil, and are regularly updated.

• If you use nix-env, run nix-env -iA nixpkgs.nil
• If you use nix profile, run nix profile install nixpkgs#nil
• If you want to compile it from source.
  1. Install stable Rust toolchain >= 1.62
  2. Install nix >= 2.4 and make the binary nix available from your PATH.
  3. Build and install via cargo install --git https://github.com/oxalica/nil nil

Flake

This repo is also packaged via Nix flakes, the language server binary package is available through the default flake output github:oxalica/nil# with the path bin/nil.

You can enable flakes support in your nix configuration, and then run nix profile install github:oxalica/nil to get nil installed. You can also use this repository as a flake input and add its output to your own flake-managed systemwide or home configuration.

Disclaimer: We ship flake.lock which is tested in CI to be working. If you use follows to override flake inputs, we provide no guarantee of whether it would still build.

Flake output structure (not necessary up-to-date):

├───devShells
│   └───(...)
└───packages
    ├───x86_64-linux
    │   ├───default: package 'nil-unstable-2022-08-04'
    │   └───nil: package 'nil-unstable-2022-08-04'
    └───(...)

Editor integration

Neovim native LSP and nvim-lspconfig

We are officially supported by nvim-lspconfig, see upstream docs.

See also the example config for testing.

Vim/Neovim with coc.nvim

Merge this setting into your coc-settings.json, which can be opened by :CocConfig.

{
  "languageserver": {
    "nix": {
      "command": "nil",
      "filetypes": ["nix"],
      "rootPatterns":  ["flake.nix"],
      // Uncomment these to tweak settings.
      // "settings": {
      //   "nil": {
      //     "formatting": { "command": ["nixpkgs-fmt"] }
      //   }
      // }
    }
  }
}

See also the example config for testing.

Vim with vim-lsp

Add the following code to your vimrc to register the LSP server. Thanks @mitchmindtree

if executable('nil')
  autocmd User lsp_setup call lsp#register_server({
    \ 'name': 'nil',
    \ 'cmd': {server_info->['nil']},
    \ 'whitelist': ['nix'],
    \ })
endif

Emacs with lsp-mode

Add the following elisp code to your configuration. (using use-package)

(use-package lsp-mode
  :ensure t)

(use-package lsp-nix
  :ensure lsp-mode
  :after (lsp-mode)
  :demand t
  :custom
  (lsp-nix-nil-formatter ["nixpkgs-fmt"]))

(use-package nix-mode
  :hook (nix-mode . lsp-deferred)
  :ensure t)

There are various other configurations to tweak it. Refer the specific manual page for more details.

Emacs with eglot

Add the following elisp code to your configuration. (using use-package)

(use-package nix-mode)
(use-package eglot
  :config
  ;; Ensure `nil` is in your PATH.
  (add-to-list 'eglot-server-programs '(nix-mode . ("nil")))
  :hook
  (nix-mode . eglot-ensure))

Vscode/Vscodium with Nix IDE

Modify the extension's settings in your settings.json.

{
  "nix.enableLanguageServer": true, // Enable LSP.
  "nix.serverPath": "nil" // The path to the LSP server executable.

  // Uncomment these to tweak settings.
  // "nix.serverSettings": {
  //   "nil": {
  //     "formatting": { "command": ["nixpkgs-fmt"] }
  //   }
  // }
}

Kate with LSP Client Plugin

Add this to your "User Server Settings" in LSP Client configuration:

{
  "servers": {
    "nix": {
      "command": ["nil"],
      "url": "https://github.com/oxalica/nil",
      "highlightingModeRegex": "^Nix$"
    }
  }
}

License

"nil" is primarily distributed under the terms of both the MIT license and the Apache License (Version 2.0).

See LICENSE-APACHE and LICENSE-MIT for details.