haskell/bytestring — pull request #9 by snoyberg (2014-01-20 09:08:42+00:00)
Title: mapM_

While this can be implemented at a high level via `mapM_ f (unpack bs)` (or instead via `index`), I've benchmarked this lower-level implementation as providing a significant performance improvement (~42% speedup in my case). I'm already including this implementation in both `conduit` and `mono-traversable`, but I believe having this in `bytestring` itself is the best option.