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About the project

treefmt is a formatting tool that saves you time: it provides developers with a universal way to trigger all formatters needed for the project in one place.


Typically, each project has its own code standards enforced by the project's owner. Any code contributions must match that given standard, i.e. be formatted in a specific manner.

At first glance, the task of code formatting may seem trivial: the formatter can be automatically triggered when you save a file in your IDE. Indeed, formatting doesn't take much effort if you're working on a single project long term: setting up the formatters in your IDE won't take much of your time, and then you're ready to go.

Contrary to that, if you're working on multiple projects at the same time, you may have to update your formatter configs in the IDE each time you switch between the projects. This is because formatter settings aren't project-specific --- they are set up globally for all projects.

Alternatively, you can trigger formatters manually, one-by-one or in a script. Actually, for bigger projects, it's common to have a script that runs over your project's directories and calls formatters consequently. But it takes time to iterate through all the files.

All the solutions take up a significant amount of time which a developer could spend doing the actual work. They also require you to remember which formatters and options are used by each project you are working on.

treefmt solves these issues.

Why treefmt?

treefmt's configuration is project-specific, so you don't need to re-configure formatters each time you switch between projects, like you have to when working with formatters in the IDE.

Contrary to calling formatters from the command line, there's no need to remember all the specific formatters required for each project. Once you set up the config, you can run the tool in any of your project's folders without any additional flags or options.

Typically, formatters have different ways to say there was a specific error. With treefmt, you get a standardized output which is easier to understand than the variegated outputs of different formatters, so it takes less time to grasp what's wrong.

In addition, treefmt works faster than the custom script solution because the changed files are cached and the formatters run only against them. Moreover, formatters are run in parallel, which makes the tool even faster.

The difference may not be significant for smaller projects, but it gets quite visible as the project grows. For instance, take the caching optimization.

It takes about 23 seconds to traverse a project of 40,559 files and no changes without caching:

traversed 41273 files
emitted 41273 files for processing
formatted 34111 files (14338 changed) in 23.679s

...while it takes 239 milliseconds to traverse the same project with caching:

traversed 41273 files
emitted 0 files for processing
formatted 0 files (0 changed) in 239ms

The tool can be invoked manually or integrated into your CI. There's currently no integration with IDEs, but the feature is coming soon.

What we still need help with

  • IDE integration: Most of developers are used to formatting a file upon save in the IDE. So far, you can't use treefmt for this purpose, but we're working on it 😀
  • Pre-commit hook: It's good to have your code checked for adherence to the project's standards before commit. treefmt pre-commit hook won't let you commit if you have formatting issues.

As a next step, learn how to install and run treefmt.

Released under the MIT License.