Some handy Template Haskell splices for including the current git hash and branch in the code of your project. Useful for including in panic messages, --version output, or diagnostic info for more informative bug reports.

{-# LANGUAGE TemplateHaskell #-}
import GitHash

panic :: String -> a
panic msg = error panicMsg
  where panicMsg =
          concat [ "[panic ", giBranch gi, "@", giHash gi
                 , " (", giCommitDate gi, ")"
                 , " (", show (giCommitCount gi), " commits in HEAD)"
                 , dirty, "] ", msg ]
        dirty | giDirty gi = " (uncommitted files present)"
              | otherwise   = ""
        gi = $$tGitInfoCwd

main = panic "oh no!"

% stack runghc Example.hs
Example.hs: [panic master@2ae047ba5e4a6f0f3e705a43615363ac006099c1 (Mon Jan 11 11:50:59 2016 -0800) (14 commits in HEAD) (uncommitted files present)] oh no!

WARNING: None of this will work in a git repository without any commits.

Since: 0.1.0.0