optional is a command line option parser and library.

YOU WRITE:

object MyAwesomeCommandLineTool extends optional.Application {
  // for instance...
  def main(count: Option[Int], file: Option[java.io.File], arg1: String) {
    [...]
  }
}

THEN YOU DO:

  scala MyAwesomeCommandLineTool --count 5 quux

AND YOUR MAIN METHOD WILL BE INVOKED SUCH THAT:

  count = Some(5)
  file = None
  arg1 = quux
  
See the example programs for many more features.

HOW IT WORKS:

  Reflection, man.

CREDITS:

  Idea and prototype implementation: DRMacIver.
   Fleshing out and awesomification: paulp.