FunctionNPhase.scala

case class FunctionNPhase[Event, States <: HList, Phases <: HList](
    function: Seq[Double] => Double,
    functionName: String,
    innerPhases: Phases
  )(implicit ev: Mapped.Aux[States, ({ type T[State] = NumericPhaseParser[Event, State] })#T, Phases])
      extends Pattern[Event, States, Double] {

    private val initialStateGetter = new (({ type U[State] = NumericPhaseParser[Event, State] })#U ~> Id) {
      override def apply[T](f: NumericPhaseParser[Event, T]): Id[T] = f.initialState
    }

    override def initialState: States = innerPhases.map(initialStateGetter)
    override def apply(event: Event, state: States): (PatternResult[Double], States) = ???
    {
      val allPhasesTogether =
        innerPhases.foldLeft((f: NumericPhaseParser[Event, _], g: NumericPhaseParser[Event, _]) => f togetherWith g)
      val (results, newState) = allPhasesTogether(event, state)
      // FIXME@trolley813: it's pseudocode, won't work
      results.map { case x => function(x.toSeq) } -> newState

    }
  }