case class Node(name: String)
case class Leaf(value: String, node: Node)
case class InternalNode(children: List[Node], node: Node)

object Node {
  implicit val show = new Show[Node] {
    override def show(node: Node): String = s"(${node.name.show})"
  }
}

def derieve[F[_] : Contravariant, A, B](f: B => A)(implicit fa: F[A]): F[B] =
  Contravariant[F].contramap(fa)(f)

object Leaf {
  implicit val show = derieve[Show, Node, Leaf](_.node)
}

object InternalNode {
  implicit val show = derieve[Show, Node, InternalNode](_.node)
}