typeclassexample.scala

//type-class 
trait Described[A] {
  def description(a: A): String
}

implicit object IntDesc extends Described[Int] {
  override def description(i: Int) = s"Int $i"
}

implicit object StrDesc extends Described[String] {
  override def description(s: String) = s"String $s"
}

implicit def listDesc[T : Described]: Described[List[T]] = 
  new Described[List[T]] {
    override def description(xs: List[T]) = {
      val describer = implicitly[Described[T]]
      val elemsDescription = (xs map describer.description).mkString(", ")
      s"List [$elemsDescription]"
    }
  }

def describe[T : Described](entity: T) = implicitly[Described[T]].description(entity)

//tests
describe(1)
describe("a")
describe(List(1, 2, 3))
describe(List(List("a", "b"), List("c")))