implicitrecursion.scala

object console extends App {


  trait Printer[T] {
    def print(t: T): String
  }

  object Printer {
    implicit val intPrinter: Printer[Int] = new Printer[Int] {
      def print(i: Int) = s"$i: Int"
    }

    implicit def optionPrinter[V](implicit pv: Printer[V]): Printer[Option[V]] =
      new Printer[Option[V]] {
        def print(ov: Option[V]) = ov match {
          case None => "None"
          case Some(v) => s"Option[${pv.print(v)}]"
        }
      }

    implicit def listPrinter[V](implicit pv: Printer[V]): Printer[List[V]] =
      new Printer[List[V]] {
        def print(ov: List[V]) = ov match {
          case Nil => "Nil"
          case l: List[V] => s"List[${l.map(pv.print).mkString(", ")}]"
        }
      }
  }

  def print[T](t: T)(implicit p: Printer[T]) = p.print(t)

  val res = print(Option(List(1, 3, 6)))
  println(s"res: ${res}")

  // res: Option[List[1: Int, 3: Int, 6: Int]]
}