Higher-order-function(고차함수)

Higher-order-function(고차함수)

https://medium.com/@lazysoul/high-order-function-%EA%B3%A0%EC%B0%A8%ED%95%A8%EC%88%98-22b147d0c4a5

함수를 인자로 받거나, 함수를 반환하는 함수

이 조건이 성립하기 위해서는 기본적으로 함수가 FirstClassCitizen이어야 함

object Main {
    @JvmStatic
    fun main(args: Array<String>) {
        println(simpleHigherOrderFunction({ x, y -> x + y }, 10, 20)) //30

        println(simpleHigherOrderFunction(sumInts, 10, 20))       //30
        println(simpleHigherOrderFunction(productInts, 10, 20))   // 200
        println(simpleHigherOrderFunction(twiceSumeInts, 10, 20)) // 60

        println(simpleHigherOrderFunction({ a, b -> a + b }, 10, 20))       //30
        println(simpleHigherOrderFunction({ a, b -> a * b }, 10, 20))       // 200
        println(simpleHigherOrderFunction({ a, b -> (a + b) * 2 }, 10, 20)) // 60
    }

    fun simpleHigherOrderFunction(sum: (Int, Int) -> Int, a: Int, b: Int): Int = sum(a, b)
    val sumInts: (Int, Int) -> Int = { a, b -> a + b }
    val productInts: (Int, Int) -> Int = { a, b -> a * b }
    val twiceSumeInts: (Int, Int) -> Int = { a, b -> (a + b) * 2 }
}