tcpoly_parseridioms.scala:18: warning: match may not be exhaustive.
It would fail on the following input: ParseResult()
        case Success(next, x) => b(next) match {
                                  ^
tcpoly_parseridioms.scala:17: warning: match may not be exhaustive.
It would fail on the following input: ParseResult()
      def apply(in: Input): ParseResult[Tuple2[T, U]] = a(in) match {
                                                         ^
tcpoly_parseridioms.scala:30: warning: match may not be exhaustive.
It would fail on the following input: ParseResult()
      case Failure(_, _) => b(in) match {
                             ^
tcpoly_parseridioms.scala:28: warning: match may not be exhaustive.
It would fail on the following input: ParseResult()
    def apply(in: Input): ParseResult[T] = a(in) match {
                                            ^
tcpoly_parseridioms.scala:39: warning: match may not be exhaustive.
It would fail on the following input: ParseResult()
    def apply(in: Input): ParseResult[U] = a(in) match {
                                            ^
Success(List(),Plus(1,2))