Best way to parse command-line parameters? [closed]

Answer 1

I've attempted generalize @pjotrp's solution by taking in a list of required positional key symbols, a map of flag -> key symbol and default options:

def parseOptions(args: List[String], required: List[Symbol], optional: Map[String, Symbol], options: Map[Symbol, String]): Map[Symbol, String] = {
  args match {
    // Empty list
    case Nil => options

    // Keyword arguments
    case key :: value :: tail if optional.get(key) != None =>
      parseOptions(tail, required, optional, options ++ Map(optional(key) -> value))

    // Positional arguments
    case value :: tail if required != Nil =>
      parseOptions(tail, required.tail, optional, options ++ Map(required.head -> value))

    // Exit if an unknown argument is received
    case _ =>
      printf("unknown argument(s): %s\n", args.mkString(", "))
      sys.exit(1)
  }
}

def main(sysargs Array[String]) {
  // Required positional arguments by key in options
  val required = List('arg1, 'arg2)

  // Optional arguments by flag which map to a key in options
  val optional = Map("--flag1" -> 'flag1, "--flag2" -> 'flag2)

  // Default options that are passed in
  var defaultOptions = Map()

  // Parse options based on the command line args
  val options = parseOptions(sysargs.toList, required, optional, defaultOptions)
}