Nu-Lint

Linter for the innovative Nu shell.

Learning to use a new shell is a radical change that can use some assistance. This project is aimed at helping new and intermediate users of the Nu shell. Nu shell has a lot of useful features not found in other scripting languages. This linter will give you hints to use all of them and even offer automatic fixes.

All rules are optional and can be disabled with a configuration file. The rule definitions are designed to be compatible with:

The standard Nu parser nu-check.
The standard Nu formatter topiary-nushell.

Example

The rule positional_to_pipeline recommends to use pipelines instead of positional arguments:

def filter-positive [numbers] { 
    $numbers | where $it > 0 
}

def filter-positive [] { 
    where $it > 0 
}

This rule in particular encourages you to use lazy pipeline input. When you evaluate a traditional positional list argument, the whole list is processed at once, but when you use implicit pipeline input (by starting the function body with where), the list processed lazily (without loading the list in memory completely at once).

CLI usage

For all available options and usage information, run:

nu-lint # Lint all Nu files in working directory
nu-lint --help

Installation

From crates.io:

cargo install nu-lint

Source

Build from source:

cargo install --path .
cargo install --git "$THIS_GIT_URL"

Nix

Run without installing (using flakes):

nix run git+https://codeberg.org/wvhulle/nu-lint

Editor extension

VS Code extension

Available at VS Code Marketplace.

Helix

Add to your ~/.config/helix/languages.toml:

[language-server.nu-lint]
command = "nu-lint"
args = ["--lsp"]

[[language]]
name = "nu"
language-servers = ["nu-lint"]

Neovim

Add to your Neovim configuration (Lua):

vim.lsp.config['nu-lint'] = {
  cmd = { 'nu-lint', '--lsp' },
  filetypes = { 'nu' },
  root_markers = { '.git' }
}
vim.lsp.enable('nu-lint')

Emacs

Add to your Emacs configuration (with Eglot, built-in since Emacs 29):

(with-eval-after-load 'eglot
  (add-to-list 'eglot-server-programs
               '(nushell-mode "nu-lint" "--lsp")))

Kate

Add to your ~/.config/kate/lspclient/settings.json:

{
  "servers": {
    "nushell": {
      "command": ["nu-lint", "--lsp"],
      "highlightingModeRegex": "^Nushell$"
    }
  }
}

Other

You can also implement your own editor extensions using the --lsp flag as in: nu-lint --lsp. This will spawn a language server compliant with the Language Server Protocol.

Configuration

Create .nu-lint.toml in your project root:

# This rule is ignored
ignored = ["snake_case_variables"]

# Set lint level of a set of rules at once.
[groups]
performance = "warning"
type-safety = "error"

# Override a single rule lievel
[rules]
prefer_pipeline_input = "hint"

Rules

You can add, remove or change rules by forking this repo and opening a PR (see ./CONTRIBUTING.md).

License

MIT

nu-lint 0.0.73