treefmt - one CLI to format the code tree

Status: beta

When working on large code trees, it's common to have multiple code formatters run against it. And have one script that loops over all of them. treefmt makes that nicer.

• A unified CLI and output
• Run all the formatters in parallel.
• Cache which files have changed for super fast re-formatting.

Just type treefmt in any folder and it reformats the whole code tree.

Design decisions

We assume that the project code is checked into source control. Therefore, the default should be to write formatter changes back in place. Options like --dry-run are not needed; the source control is relied upon to revert or check for code changes.

treefmt is responsible for traversing the file-system and mapping files to specific code formatters.

Only one formatter per file. treefmt enforces that only one tool is executed per file. Guaranteeing two tools to produce idempotent outputs is quite tricky.

Usage

$ treefmt --help

``` treefmt 0.2.5 ✨ format all your language!

USAGE: treefmt [FLAGS] [OPTIONS] [paths]...

FLAGS: --clear-cache Clear the evaluation cache. Use in case the cache is not precise enough --fail-on-change Exit with error if any changes were made. Useful for CI -h, --help Prints help information --init Create a new treefmt.toml -q, --quiet No output printed to stderr --stdin Format the content passed in stdin -V, --version Prints version information -v, --verbose Log verbosity is based off the number of v used

OPTIONS: --tree-root Set the path to the tree root directory. Defaults to the folder holding the treefmt.toml file -C Run as if treefmt was started in instead of the current working directory [default: .]

ARGS: ... Paths to format. Defaults to formatting the whole tree ```

Configuration format

In order to use treefmt in the project, treefmt.toml should exists in the root folder. For example, we want to use nixpkgs-fmt on our Nix project and rustfmt on our Rust project, then the treefmt.toml will be written as follows:

``` [formatter.nix] command = "nixpkgs-fmt" includes = ["*.nix"]

[formatter.rust] command = "rustfmt" options = ["--edition", "2018"] includes = ["*.rs"] ```

Use cases

CLI usage

As a developer, I want to run treefmt in any folder and it would automatically format all of the code, configured for the project. I don't want to remember what tool to use, or their magic incantation.

Editor integration

Editors often want to be able to format a file, before it gets written to disk.

Ideally, the editor would pipe the code in, pass the filename, and get the formatted code out. Eg: cat ./my_file.sh | treefmt --stdin my_file.sh > formatted_file.sh

CI integration

The --fail-on-change flag can be used to exit with error if any files were re-formatted.

Eg:

```sh

!/usr/bin/env bash

set -euo pipefail

Format all of the code and exit with error if there are any changes

treefmt --fail-on-change ```

Interfaces

In order to keep the design of treefmt simple, we ask code formatters to adhere to the following specification.

treefmt formatter spec

If they don't, the best is to create a wrapper script that transforms the usage to match that spec.

Related projects

• EditorConfig: unifies file indentations configuration on a per-project basis.
• prettier: and opinionated code formatter for a number of languages.
• Super-Linter: a project by GitHub to lint all of the code.
• pre-commit: a framework for managing and maintaining multi-language pre-commit hooks.

Contributing

All contributions are welcome! We try to keep the project simple and focused so not everything will be accepted. Please refer to Contributing guidelines for more information.

License

Unless explicitly stated otherwise, any contribution intentionally submitted for inclusion in the work by you shall be licensed under the MIT license, without any additional terms or conditions.