Kotlin code sample

OperatorOverload.kt

fun main() {
    val s = Square(2.0)
    println(s.area()) // Prints 4.0, duh!
    println(s - Square(3.0)) // Prints -5.0, Sweet!
}

data class Square (val side: Double) {
    operator fun minus(other: Square): Double {
        return this.area() - other.area()
    }

    fun area(): Double {
        return side * side
    }
}