Static Duck Typing

StructuralTypeSample.scala

class Duck {
    def squawk = println("Quack")
    def waddle = println("Duck walk")
}
class Pengiun {
    def squawk = println("Squeek")
    def waddle = println("Penguin walk")
}
class Person { }

// everybody's heard about the word...
def birdIsTheWord(bird : { def squawk; def waddle}) = {
    bird.squawk
    bird.waddle
}

birdIsTheWord(new Duck())      // prints "Quack" then "Duck walk"
birdIsTheWord(new Penguin())   // prints "Squeek" then "Penguin walk"
birdIsTheWord(new Person())    // Will not compile