by Jake Worth on March 20, 2018

Last October I discovered an interesting Github issue, Elixir-Lang #6643. It was opened José Valim, the creator of Elixir.

Here's part of the introduction to this issue:

Elixir master now includes a code formatter that automatically formats your code according to a consistent style.

We want to convert Elixir's codebase to use the formatter on all files. We understand this means a lot of code churn now but, on the positive side, it means we can automatically enforce and/or format future contributions, making it easier for everyone to contribute to Elixir.¹

This issue set off a massive refactoring project to get Elixir conforming with its new formatter. Today, new pull requests to Elixir must pass through the formatter without requiring changes. I think this will have a ripple effect on every Elixir project in production.

While closing this issue, José provided the following statistics on the refactor:

• 425 files were changed
• 214 pull requests were opened
• 84 committers contributed
• 368 commits were added

Most interestingly to me, the entire project took just four days to complete. I think this shows the power of the community and the effectiveness of the tool.

This is a big change that affects everybody who writes Elixir. As an open-source Elixir project maintainer, it led me to some questions, such as: what is autoformatting? Why should I care? What is it going to do to my code?

After some research, my conclusion is we should all format our Elixir code now. It's the future of this language.

I started thinking about this tool and its importance a lot this year, leading to this blog post. Continued investigation led to a talk that I presented at ElixirDaze 2018 in Denver, CO. I focused on the history of autoformatting, arguments for and against the practice, and practical applications for a production Elixir application.

Want to learn more? Check out the recording of my talk at ElixirDaze, and follow along with the slides.

Elixir mixologists of every experience level will leave this talk with a better understanding of this important tool, and a deeper grasp of the persistent debate around code style. Thanks to ElixirDaze, the great attendees I met, my friends at the ChicagoElixir Meetup for vetting my talk, and Hashrocket for continuing to sponsor my public speaking adventures.

Photo credit: Samuel Zeller