chop a command/program invocation into pieces

 Similar to the optparse-applicative package, but less features, more
 flexibility and more evil. The main differences are:
 .
  * Provides a pure interface by default
  * Exposes an evil monadic interface, which allows for much nicer
    binding of command part results to some variable name.
  * The monadic interface allows much clearer definitions of
    command parses with (nested) subcommands. No pesky sum-types are
    necessary.
 .
 This package provides a library for the Haskell programming language.
 See http://www.haskell.org/ for more information on Haskell.