nixfmt-tree

A zero-setup [treefmt](https://treefmt.com/) starter to get started using the [official Nix formatter](https://github.com/NixOS/nixfmt). - For `nix fmt` to format all Nix files, add this to the `flake.nix` outputs: ```nix formatter.${system} = nixpkgs.legacyPackages.${system}.nixfmt-tree; ``` - The same can be done more efficiently with the `treefmt` command, which you can get in `nix-shell`/`nix develop` by extending `mkShell` using ```nix mkShell { packages = [ pkgs.nixfmt-tree ]; } ``` You can then also use `treefmt` in a pre-commit/pre-push [Git hook](https://git-scm.com/docs/githooks) and with your editor's format-on-save feature. - To check formatting in CI, run the following in a checkout of your Git repository: ``` treefmt --ci ``` For more flexibility, you can customise this package using ```nix pkgs.nixfmt-tree.override { settings = { /* additional treefmt config */ }; runtimeInputs = [ /* additional formatter packages */ ]; } ``` You can achieve similar results by manually configuring `treefmt`: ```nix pkgs.treefmt.withConfig { runtimeInputs = [ pkgs.nixfmt ]; settings = { # Log level for files treefmt won't format on-unmatched = "info"; # Configure nixfmt for .nix files formatter.nixfmt = { command = "nixfmt"; includes = [ "*.nix" ]; }; }; } ``` Alternatively you can switch to the more fully-featured [treefmt-nix](https://github.com/numtide/treefmt-nix).