git-vogue - A framework for pre-commit checks

Intended to be used as a git pre-commit hook, git-vogue encourages developers to keep their Haskell code "en vogue" by providing a framework for checking code quality and some supporting plugins.

Currently, git-vogue ships with the following plugins:

• cabal
• hlint
• stylish-haskell with automatic fixing
• ghc-mod

Quickstart

cabal install git-vogue

If you wish to set up pre-commit hooks (recommended):

git vogue init

With pre-commit hooks set up, git vogue check will be run before every commit. If you wish to check the whole repository, run git vogue check --all.

You can attempt to automatically rectify any problems discovered via git vogue fix and git vogue fix --all. The only plugin that currently supports this auto-fixing is stylish-haskell.

Plugin discovery/disabling

Running git-vogue plugins will show you which plugins are currently detected and enabled. This set can be tweaked on a per-repository basis with git-vogue enable and git-vogue disable.

Alternatively you can disable plugins on a per-system basis by adding the file name to the vogue.disable key in your git global configuration:

git config --global --add vogue.disable cabal

Plugins

cabal

Checks your .cabal file for packaging problems. Can not fix problems automatically.

hlint

Checks .hs files for linting issues, respects HLint.hs in the top level of the repository. Can not fix problems automatically.

ghc-mod

Checks .hs files (excluding HLint.hs and Setup.hs) as per ghc-mod check. ghc-mod can be temperamental, so if this fails to run the plugin will allow the commit to pass. Can not fix problems automatically.

stylish-haskell

Checks if .hs files would have been modified by stylish-haskell. Respects .stylish-haskell.yaml. Can fix problems automatically.

Uninstalling

To remove a git-vogue init configured pre-commit hook, run:

rm .git/hooks/pre-commit

Here are instructions for uninstalling a cabal package.

Philosophy

At Anchor Engineering, we're pretty un-dogmatic about using one editor or even one OS for development. As such, we've found ourselves in need of a common benchmark for linting, formatting and code quality checks.

We wanted a tool that would:

• Install in one command
• Require nothing to be learned for a new developer
• Tell that developer what they need to fix in the code that they modify and that code only.

git-vogue aims to satisfy these needs, whilst saving developers from the drudgery of installing, configuring and running each of these tools independently.

Plugin specification

The interface for an executable (to be called by git-vogue) is a command line argument, one of {check,fix,name}, followed by a list of files that are to be checked, and then a list of all the files in the repository that are not ignored. These lists are newline separated.

The plugin can assume that the CWD will be set to the top-level directory of the package.

Here's how you might run stylish-haskell on all files in the current directory:

cd dir-to-check;
path-to-libexec/git-vogue-stylish check "$(find .)" "$(find .)"

Invariants for well-behaved plugin commands

• name will return a human-readable name one line
• check will not modify any files
• check will exit with a return code of:
  • No errors - 0
  • Errors need fixing - 1
  • Catastrophic failure to check - 2
• fix is idempotent
• fix will exit with a return code of:
  • The code is now good (changes may or may not have been made) - 0
  • Some errors remain - 1
  • Catastrophic failure to check - 2
• If fix returns "success" (return code 0), check must no longer fail