steamroller

🚂 Steamroller
==============
![Build Badge](https://github.com/old-reliable/steamroller/workflows/build/badge.svg)
Steamroller is an opinionated Erlang code formatter. Uniformity is inevitable.
![Austin Powers Steamroller Gif](https://thumbs.gfycat.com/MassiveGlossyAmericantoad-size_restricted.gif)
Upset your colleagues by autoformatting their code.
This rebar3 plugin is still under development but should be considered reasonably stable. The
Erlang abstract syntax tree is checked before and after formatting to make sure that the formatted
file is equivalent to the original.
Steamroller should be used as part of your CI to enforce a consistent style across your codebase.
## Use
Add steamroller to your rebar config:
    {plugins, [steamroller]}.
Then ask it to steamroll your code directly in an existing application:
    $ rebar3 steamroll
    ===> Fetching steamroller
    ===> Compiling steamroller
    <Steamroller Output>
## Configure
Steamroller comes with sensible default configuration. If you want, you can configure the line
length, indent, and input files from your rebar config:
    {
      steamroller,
      [
        {line_length, 100},
        {indent, 2},
        {inputs, ["rebar.config", "{src,test}/**/*.{[he]rl,app.src}"]}
      ]
    }.
## Editor Integration
### Vim
You can use steamroller from vim with [Neoformat](https://github.com/sbdchd/neoformat).
Install Neoformat and then paste the below into your vimrc.
```viml
" Erlang autoformat
let g:neoformat_erlang_steamroller = {
  \ 'exe': 'rebar3',
  \ 'args': ['steamroll -f'],
  \ 'stdin': 0,
  \ 'replace': 1,
  \ }
let g:neoformat_enabled_erlang = ['steamroller']
autocmd BufWritePre rebar.config,*.[he]rl,*.app.src Neoformat steamroller
```
### Visual Studio Code
You can use steamroller from Visual Studio Code with the
[Erlang Formatter](https://marketplace.visualstudio.com/items?itemName=szTheory.erlang-formatter)
extension created by [szTheory](https://github.com/szTheory).
## CI
To check that code is properly formatted as part of your CI:
    $ rebar3 steamroll --check
The exit code will be non-zero if the code has not been formatted before being committed.
## Build
    $ rebar3 compile
## Test
    $ rebar3 test
## Dialyzer
Dialyzer is Erlang's static analysis tool.
    $ rebar3 dialyzer
## Local Development
In order to use steamroller locally on itself you need to symlink the repo into the \_checkouts
directory:
    cd $local_steamroller_repo
    mkdir _checkouts
    ln -s $PWD ./_checkouts/steamroller
Rebar3 will use the version of steamroller in the \_checkouts directory with higher priority than
the version specified in the rebar.config. There's a line in the rebar.config (see `overrides`)
which prevents infinite plugin loops when using steamroller locally like this.