nil: NIx Language server

An incremental analysis assistant for writing in Nix.

See release notes for changelog between releases.

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 available in NixOS/nixpkgs under attribute nil, and is 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 sure the binary nix is in your PATH.
  3. Build and install via cargo install --git https://github.com/oxalica/nil nil

Install with Flake

This repo is also packaged via Nix flakes. The language server package is available in the default flake output github:oxalica/nil#, under bin/nil.

To install, run nix profile install github:oxalica/nil. Alternatively, you can use this repository as a flake input, and add its output to your own flake-managed system-wide and/or home configurations.

Disclaimer: The flake.lock we ship is tested in CI. If you use follows to override flake inputs, we do not guarantee that it will build.

Flake output structure (not necessarily 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, also the example config for testing.

⚠️ There is a known performance issue for semantic highlighting with neovim native LSP. See more details in oxalica#83

Vim/Neovim with coc.nvim

Merge this setting into your coc-settings.json (open with :CocConfig).

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

See 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. Refer to 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.