First-class & Higher-order function (고차함수)

First class funtions : just a feature that a programme language ether has or does not have.All it means is that all functions are values. There are no first class functions in practice. It's just a concept

Higher-order function: There are higher-order functions in practice. It's possible because the langauge supports the first-class function.

3/23

higher-order function? functions that work with other functions or they operate on or with other functions
-they can accept other functions as arguments
-return a function

먼저 다른 function을 argument로 받아들이는 예시를 한 번 보자

function callTwice(func) {
    func();
    func();
}

function rollDie() {
    const roll = Math.floor(Math.random() * 6) + 1
    console.log(roll)
}

callTwice(rollDie)

저기 보면 func를 argument로 두번 불러주는데
밑에 argument에 넣어줄 function 써주고
첫번째 function call 해주면 실행 됨 ㅋㅋ