View Source Styler
Styler is an AST-rewriting tool. Think of it as a 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. Hence, mix style
!
Styler is configuration-free. Like mix format
, it runs based on the inputs
from .formatter.exs
and has opinions rather than configuration.
installation
Installation
Add :styler
as a dependency to your project's mix.exs
:
def deps do
[
{:styler, "~> 0.2", only: [:dev, :test], runtime: false},
]
end
usage
Usage
$ mix style
This will rewrite your code according to the Styles of Styler
and format it.
Run mix help style
for more details on arguments and flags.
replacing-mix-format
Replacing mix format
As stated above, Styler
takes a cue from Elixir's Formatter and offers no configuration. Instead, it harnesses the same .formatter.exs
file as Formatter to know which files within your project it should style.
Styler
wraps up its work by running its rewrites through the Formatter - in fact, it's meant to be a complete stand-in for mix format
. You can alias it as format
to quickly standardize its use across your project and save yourself the work of having to update existing formatter-related CI scripts and documentation.
def aliases do
[
# `mix format` will now actually run `mix style` behind the scenes
# saving you from updating your existing CI scripts etc!
format: "style"
]
end
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.
credo-rules-styler-replaces
Credo Rules Styler Replaces
Credo.Check | Styler.Style | Style notes |
---|
| Credo.Check.Consistency.MultiAliasImportRequireUse
| Styler.Style.ModuleDirectives
| always expands A.{B, C}
| Credo.Check.Readability.AliasOrder
| Styler.Style.ModuleDirectives
|
| Credo.Check.Readability.BlockPipe
| Styler.Style.Pipes
|
| Credo.Check.Readability.LargeNumbers
| Styler.Style.Simple
| fixes bad underscores, ie: 100_00
| Credo.Check.Readability.ModuleDoc
| Styler.Style.ModuleDirectives
| adds @moduledoc false
| Credo.Check.Readability.MultiAlias
| Styler.Style.ModuleDirectives
|
| Credo.Check.Readability.SinglePipe
| Styler.Style.Pipes
|
| Credo.Check.Readability.StrictModuleLayout
| Styler.Style.ModuleDirectives
| potentially destructive! (see moduledoc)
| Credo.Check.Readability.UnnecessaryAliasExpansion
| Styler.Style.ModuleDirectives
|
| Credo.Check.Refactor.PipeChainStart
| Styler.Style.Pipes
|
If you're using Credo and Styler, we recommend disabling these rules in Credo to save on unnecessary checks in CI.
styler-and-comments
Styler and Comments...
Styler is currently unaware of comments, so you may find that they end up in really odd spots after a rewrite.
If you find that a comment was put somewhere weird after using Styler, you'll just have to manually put it back where you want it after. Feel free to grumble about it in an Issue so that we can properly prioritize making this work better in the future.
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.
elixir-s-formatter
Elixir's Formatter
The low-hassle, (almost) no-config design of mix format
greatly influenced the implementation of mix style
.