LeftRightFeedbacksReactive.swift

func leftEffect(inputLevels: Levels) -> SignalProducer<Event, Never> {
    // this is the stop condition to our Spin
    guard inputLevels.left != inputLevels.right else { return .empty }

    // this is the regulation for the left level
    if inputLevels.left < inputLevels.right {
        return SignalProducer(value: .increaseLeft)
    }  else {
        return SignalProducer(value: .decreaseLeft)
    }
}

func rightEffect(inputLevels: Levels) -> SignalProducer<Event, Never> {
    // this is the stop condition to our Spin
    guard inputLevels.left != inputLevels.right else { return .empty }

    // this is the regulation for the right level
    if inputLevels.right < inputLevels.left {
        return SignalProducer(value: .increaseRight)
    }  else {
        return SignalProducer(value: .decreaseRight)
    }
}