perm

permutation Applicative and Monad with many mtl instances

https://github.com/sonyandy/perm

Latest on Hackage:0.4.0.0

This package is not currently in any snapshots. If you're interested in using it, we recommend adding it to Stackage Nightly. Doing so will make builds more reliable, and allow stackage.org to host generated Haddocks.

BSD-3-Clause licensed by Andy Sonnenburg
Maintained by Andy Sonnenburg

Based on "Parsing Permutation Phrases", by Arthur Baars, Andres Loeh and S. Doaitse Swierstra, Haskell Workshop 2001. The implementation given here does not include explicit optional actions, and instead implements Alternative and MonadPlus. m <*> (lift n <|> pure a) should be used where addOpt m a n would be used.