functor Driver(P: PPC): DRIVER = struct
  structure P = P

  type config = {
    file: string option,
    includeDirs: string list
  }

  val initConfig: config = { file = NONE, includeDirs = [] }

  fun die msg = (printLn msg; Posix.Process.exit $ Word8.fromInt 1)

  fun parseCmdArgs { file, includeDirs } [] =
    if file = NONE then
      die "missing input file"
    else
      { file, includeDirs = rev includeDirs }
    | parseCmdArgs _ ("-I" :: []) =
        die "-I: expected directory path after flag"
    | parseCmdArgs { file, includeDirs } ("-I" :: path :: tail) =
        parseCmdArgs { file, includeDirs = path :: includeDirs } tail
    | parseCmdArgs { file, includeDirs } (arg :: tail) =
      if String.sub (arg, 0) = #"-" then
        die $ arg ^ ": unknown flag"
      else
        case file of
          NONE => parseCmdArgs { file = SOME arg, includeDirs } tail
        | SOME _ => die $ arg ^ ": file already specified"

  fun exec () =
  let
    val config = parseCmdArgs initConfig (CommandLine.arguments ())
    val fname = valOf $ #file config
  in
    P.debugPrint fname (#includeDirs config)
  end
end