stackable modifications

gistfile1.scala

trait Animal{
  println ("creating Animal")
  def speak: String
}

trait PrettyAnimal extends Animal{
  println ("creating Pretty Animal")
  abstract override def speak = s"Pretty(${super.speak})"
}

trait Cow extends Animal {
  println ("creating Cow")
  override def speak: String = "moo"
}

object animals {
  val cow = new Cow{}
  cow.speak

  val prettyCow = new Cow with PrettyAnimal
  prettyCow.speak

}