View Source Styler

Styler is an Elixir formatter plugin that's combination of mix format and mix credo, except instead of telling you what's wrong, it just rewrites the code for you to fit its style rules.

installation

Installation

  1. Add :styler as a dependency to your project's mix.exs:
def deps do
  [
    {:styler, "~> 0.5", only: [:dev, :test], runtime: false},
  ]
end
  1. Add Styler as a plugin to your .formatter.exs file
[
  plugins: [Styler],
  line_length: 100_000
]

usage

Usage

Styler is just a mix format plugin, so now your files will be styled whenever they're formatted.

$ mix format

Expect the initial styling of an existing codebase to take a while as it styles existing files and writes them to disk. Future runs will be just as fast as you're use to though.

styles

Styles

You can find the currently-enabled styles in the Mix.Tasks.Style module, inside of its @styles module attribute. Each Style's moduledoc will tell you more about what it rewrites.

examples

Examples

The best place to get an idea of what sorts of changes Styler makes is by looking at its tests!

Someday we'll announce Styler to the world, and hopefully by then we have some examples written into this here README :)

credo-rules-styler-replaces

Credo Rules Styler Replaces

Credo.CheckStyler.StyleStyle notes
Credo.Check.Consistency.MultiAliasImportRequireUseStyler.Style.ModuleDirectivesalways expands A.{B, C}
Credo.Check.Readability.AliasOrderStyler.Style.ModuleDirectives
Credo.Check.Readability.BlockPipeStyler.Style.Pipes
Credo.Check.Readability.LargeNumbersStyler.Style.Simplefixes bad underscores, ie: 100_00
Credo.Check.Readability.ModuleDocStyler.Style.ModuleDirectivesadds @moduledoc false
Credo.Check.Readability.MultiAliasStyler.Style.ModuleDirectives
Credo.Check.Readability.SinglePipeStyler.Style.Pipes
Credo.Check.Readability.StrictModuleLayoutStyler.Style.ModuleDirectivespotentially destructive! (see moduledoc)
Credo.Check.Readability.UnnecessaryAliasExpansionStyler.Style.ModuleDirectives
Credo.Check.Refactor.PipeChainStartStyler.Style.Pipes
Credo.Check.Refactor.FilterCountStyler.Style.Pipes(in pipes only)
Credo.Check.Refactor.MapJoinStyler.Style.Pipes(in pipes only)
Credo.Check.Refactor.MapIntoStyler.Style.Pipes(in pipes only)

If you're using Credo and Styler, we recommend disabling these rules in Credo to save on unnecessary checks in CI.

thanks-inspiration

Thanks & Inspiration

sourceror

Sourceror

This work was inspired by earlier large-scale rewrites of an internal codebase that used the fantastic tool Sourceror.

The initial implementation of Styler used Sourceror, but Sourceror's AST-embedding comment algorithm slows Styler down to the point that it's no longer an appropriate drop-in for mix format.

Still, we're grateful for the inspiration Sourceror provided and the changes to the Elixir AST APIs that it drove.

The AST-Zipper implementation in this project was forked from Sourceror's implementation.

credo

Credo

Similarly, this project originated from one-off scripts doing large scale rewrites of an enormous codebase as part of an effort to enable particular Credo rules for that codebase. Credo's tests and implementations were referenced for implementing Styles that took the work the rest of the way. Thanks to Credo & the Elixir community at large for coalescing around many of these Elixir style credos.