optparse-applicative is a haskell library for parsing options on the
command line, providing a powerful applicative interface for composing
these options.

optparse-applicative takes care of reading and validating the
arguments passed to the command line, handling and reporting errors,
generating a usage line, a comprehensive help screen, and enabling
context-sensitive bash completions.

Homepage:
http://hackage.haskell.org/package/optparse-applicative
