This library provides an easy way to define command line parsers.
Most users will want to use the System.Console.CmdArgs.Implicit module,
whose documentation contains an example.

* System.Console.CmdArgs.Explicit provides a way to write command line parsers
  for both single mode programs (most programs) and multiple mode programs
  (e.g. darcs or cabal). Parsers are defined by constructing a data structure.

* System.Console.CmdArgs.Implicit provides a way to concisely define
  command line parsers, up to three times shorter than getopt.
  These parsers are translated into the Explicit data type.

* System.Console.CmdArgs.GetOpt provides a wrapper allowing compatiblity
  with existing getopt parsers, mapping to the Explicit data type.

For a general reference on what command line flags are commonly used,
see http://www.faqs.org/docs/artu/ch10s05.html.