Functional Kotlin

Identity and constant

Identity and constant are straightforward functions. The identity function returns the same value provided as parameter; similar to additive and multiplicative identity property, adding 0 to any number is still the same number.

The constant<T, R>(t: T) function returns a new function that will always return the t value:

fun main(args: Array<String>) {   val oneToFour = 1..4   println("With identity: ${oneToFour.map(::identity).joinToString()}") //1, 2, 3, 4   println("With constant: ${oneToFour.map(constant(1)).joinToString()}") //1, 1, 1, 1   }

We can rewrite our fizzBuzz value using constant:

fun main(args: Array<String>) {   val fizz = PartialFunction({ n: Int -> n % 3 == 0 }, constant("FIZZ"))   val buzz = PartialFunction(