A practical example of subtype polymorphism in Scala

subtypePolymorphismExample.scala

trait Jsonable{
  def toJson: String
}

case class Picture(name: String, uri: String) extends Jsonable{
  override def toJson = s"picture ${name}"
}

case class Attachment(name: String, uri: String, visible: Boolean) extends Jsonable{
  override def toJson = s"attachment ${name}"
}

val picture: Jsonable = new Picture("mypic", "mypicurl")
val attachment: Jsonable = new Attachment("myattachment", "myurl", false)

println(picture.toJson)
println(attachment.toJson)