statix

Lints and suggestions for the Nix programming language.

statix highlights antipatterns in Nix code. statix --fix can fix several such occurrences.

For the time-being, statix works only with ASTs produced by the rnix-parser crate and does not evaluate any nix code (imports, attr sets etc.).

Examples

$ statix tests/c.nix
[W04] Warning: Assignment instead of inherit from
   ╭─[tests/c.nix:2:3]
   │
 2 │   mtl = pkgs.haskellPackages.mtl;
   ·   ───────────────┬───────────────
   ·                  ╰───────────────── This assignment is better written with inherit
───╯

$ statix --fix --dry-run tests/c.nix
--- tests/c.nix
+++ tests/c.nix [fixed]
@@ -1,6 +1,6 @@
 let
-  mtl = pkgs.haskellPackages.mtl;
+  inherit (pkgs.haskellPackages) mtl;
 in
 null

Installation

statix is available via a nix flake:

# build from source
nix build git+https://git.peppe.rs/languages/statix
./result/bin/statix --help

# statix also provides a flake app
nix run git+https://git.peppe.rs/languages/statix -- --help

# save time on builds using cachix
cachix use statix

Usage

Basic usage is as simple as:

# recursively finds nix files and raises lints
statix /path/to/dir

# ignore generated files, such as Cargo.nix
statix /path/to/dir -i '*Cargo.nix'

# see `statix -h` for a full list of options

Certain lints have suggestions. Apply suggestions back to the source with:

statix --fix /path/to/file

# show diff, do not write to file
statix --fix --dry-run /path/to/file

statix supports a variety of output formats; standard, json and errfmt:

statix /path/to/dir -o json
statix /path/to/dir -o errfmt # singleline, easy to integrate with vim

Architecture

statix has the following components:

bin: the CLI/entrypoint
lib: library of lints and utilities to define these lints
vfs: virtual filesystem
macros: procedural macros to help define a lint

`bin`

This is the main point of interaction between statix and the end user. It's output is human-readable and should also support JSON/errorfmt outputs for external tools to use.

`lib`

A library of AST-based lints and utilities to help write those lints. It should be easy for newcomers to write lints without being familiar with the rest of the codebase.

`vfs`

VFS is an in-memory filesystem. It provides cheap-to-copy handles (FileIds) to access paths and file contents.

`macros`

This crate intends to be a helper layer to declare lints and their metadata.

TODO

Offline documentation for each lint
Test suite for lints and suggestions
Vim plugin (qf list population, apply suggestions)
Resolve imports and scopes for better lints
Add silent flag that exits with status

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