typeclasses1.scala

// Our generic interface
trait Animal {
  def voice: String
}

// Pure definitions
case class Dog()
case class Cat()

// Implementation 1
class DogAnimal extends Animal {
  override def voice: String = "woof!"
}

// Implementation 2
class CatAnimal extends Animal {
  override def voice: String = "meow!"
}

// Generic function
def say(animal: Animal) = println(animal.voice)

// Usage
say(new DogAnimal) // prints "woof!"
say(new CatAnimal) // prints "meow!"