nixfmt: An opinionated formatter for Nix

[ development, library, mpl ] [ Propose Tags ]

A formatter for Nix that ensures consistent and clear formatting by forgetting all existing formatting during parsing.

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Versions [RSS] [faq] 0.3.0, 0.4.0
Change log
Dependencies base (>=4.12.0 && <4.14), cmdargs (>=0.10.20 && <0.11), directory (>=1.3.3 && <1.4), filepath (>=1.4.2 && <1.5), ghcjs-base (>=0.2.0 && <0.3), megaparsec (>=7.0.5 && <8.1), nixfmt, parser-combinators (>=1.0.3 && <1.3), safe-exceptions (>=0.1.7 && <0.2), text (>=1.2.3 && <1.3), unix (>=2.7.2 && <2.8) [details]
License MPL-2.0
Copyright 2019 Serokell, 2019 Lars Jellema
Author Lars Jellema
Revised Revision 1 made by LarsJellema at 2020-03-13T16:56:08Z
Category Development
Home page
Bug tracker
Source repo head: git clone git://
Uploaded by gromak at 2020-02-10T15:10:26Z
Distributions NixOS:0.4.0
Executables js-interface, nixfmt
Downloads 707 total (11 in the last 30 days)
Rating 1.75 (votes: 1) [estimated by Bayesian average]
Your Rating
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Status Hackage Matrix CI
Docs available [build log]
Last success reported on 2020-02-10 [all 1 reports]


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Note: This package has metadata revisions in the cabal description newer than included in the tarball. To unpack the package including the revisions, use 'cabal get'.

Maintainer's Corner

For package maintainers and hackage trustees


Readme for nixfmt-0.4.0

[back to package description]


nixfmt is a formatter for Nix code, intended to easily apply a uniform style.

You are encouraged to test this out on your code and submit any undesirable formatting you find as an issue

Build Status Cachix


  • nixfmt is in nixpkgs master as of 2019-09-04:

    nix-env -iA nixpkgs.nixfmt
  • To get the most recent version, install from master:

    # Optional: use cachix to get cached builds even for master
    cachix use nixfmt
    nix-env -f -i


With Nix

Haskell dependencies will be built by Nix.

  • Enter nix-shell
  • Build with cabal new-build

Without Nix

Haskell dependencies will be built by Cabal.

  • Build with cabal new-build


  • nixfmt < input.nix – reads Nix code form stdin, formats it, and outputs to stdout
  • nixfmt file.nix – format the file in place

For Contributors

We welcome issues and pull requests on GitHub.

About Serokell

nixfmt is maintained and funded with ❤️ by Serokell. The names and logo for Serokell are trademark of Serokell OÜ.

We love open source software! See our other projects or hire us to design, develop and grow your idea!