FlipFlap.scala

trait FlipFlap[A, B] {
  def doFlipFlap(x: A): B
}

class FlipFlapOps[A, B](v: A, f: FlipFlap[A, B]) {
  def flipFlap = f.doFlipFlap(v)
}

object Main {
  implicit def intFlipFlap = new FlipFlap[Int, Int] {
    def doFlipFlap(x: Int) = -x
  }

  implicit def stringFlipFlap = new FlipFlap[String, String] {
    def doFlipFlap(x: String) = x.reverse
  }

  implicit def pairListFlipFlap[A1, A2] = new FlipFlap[List[Pair[A1, A2]], List[Pair[A2, A1]]] {
    def doFlipFlap(x: List[Pair[A1, A2]]) = x.map(_.swap)
  }

  implicit def mapFlipFlap[K, V] = new FlipFlap[Map[K, V], Map[V, K]] {
    def doFlipFlap(x: Map[K, V]) = Map() ++ x.map(_.swap)
  }

  implicit def toAnyFlipFlapWrapper[A](value: A)(implicit implicitFlipFlap: FlipFlap[A, A]) =
    new FlipFlapOps(value, implicitFlipFlap)

  implicit def toPairListFlipFlapWrapper[A1, A2](value: List[Pair[A1, A2]])(implicit implicitFlipFlap: FlipFlap[List[Pair[A1, A2]],
    List[Pair[A2, A1]]]) =
      new FlipFlapOps(value, implicitFlipFlap)

  implicit def toMapFlipFlapWrapper[K, V](value: Map[K, V])(implicit implicitFlipFlap: FlipFlap[Map[K, V], Map[V, K]]) =
    new FlipFlapOps(value, implicitFlipFlap)

  def main(args: Array[String]) {
    println(1.flipFlap)
    println("hello".flipFlap)

    println(List(1 -> 2, 3 -> 4).flipFlap)
    println(List(1, 2).flipFlap) // Compiling error

    println(Map(
      "Dog" -> "Wan",
      "Cat" -> "Nyan"
    ).flipFlap)
  }
}