Maybet is a haskell monad transformer that adds maybe semantics to an existing monad, making it able to fail (i.e. return nothing) or be successful (return the result wrapped in a just). if you don't know what a haskell monad is, you can just ignore this package.

this package provides a library for the haskell programming language, compiled for profiling. see http://www.haskell.org/ for more information on haskell.