Sample code from [Type classes in Scala](https://blog.scalac.io/2017/04/19/typeclasses-in-scala.html)

```scala
object TypeClasses0 {

  trait Show[A] {
    def show(a: A): String
  }

  object Show {
    val intCanShow: Show[Int] = new Show[Int] {
      def show(int: Int) = s"int $int"
    }
  }

  def main(args: Array[String]): Unit = {
    import Show._
    println( intCanShow.show(20) )
  }

}
```