git-fmt

Custom git command for formatting code. git-fmt provides a wrapper around omnifmt, an automatic code formatter. It adds the ability to operate on specific tracked files in the repository.

Formatted code is:

• Easier to write: never worry about minor formatting concerns while hacking away.
• Easier to read: when all code looks the same you need not mentally convert others' formatting style into something you can understand.
• Easier to maintain: mechanical changes to the source don't cause unrelated changes to the file's formatting; diffs show only the real changes.
• Uncontroversial: never have a debate about spacing or brace position ever again.

(Bullet points taken from https://blog.golang.org/go-fmt-your-code.)

Installing

Installing git-fmt is easiest done using either stack (recommended) or Cabal.

Using stack:

stack install git-fmt
export PATH=$PATH:~/.local/bin

Using Cabal:

cabal-install git-fmt
export PATH=$PATH:~/.cabal/bin

Usage

The git-fmt binary provides an interface for selecting files and piping them through external pretty-printers. It supports both prettifying the files immediately and performing dry-runs to see which files are ugly. Given that it uses the omnifmt library underneath, the syntax and features are quite similar. The main difference is that git-fmt restricts files to being tracked by the git repository and that by default it only operates on files in the index.

The basics:

git-fmt operates only on tracked git files (thus it implicitly respects the '.gitignore' file). By default it operates on files in the index (i.e., --operate-on head). It is possible to operate on all tracked files (--operate-on-tracked) or on a specific reference (--operate-on REF). The REF argument is passed directly into git diff REF --name-only, so you can even play with ranges such as master....

Passing arguments to git-fmt will narrow down the operation files. For example, git fmt --operate-on-tracked src/ will format all tracked files under 'src/' and git fmt --operate-on head src/ will format all files in the index under 'src/'.

Modes:

git-fmt can run in three different modes, normal, dry-run and diff.

The normal and dry-run modes act the same as omnifmt. Diff mode however uses git diff as opposed to diff. By default the diff isn't paged, so to get output similar to git diff or git log it is recommended to use [-p|--paginate], e.g., git -p fmt -m diff.

NB: it isn't possible to pipe the diff into git apply due to the destination file path header.

Configuration

git-fmt delegates to omnifmt for configuration, see here for documentation and examples.