Closures

클로저 혹은 람다표현식은 익명타입입니다. 이들은 Fn, FnMut, FnOnce 라는 특별한 트레이트를 구현합니다.

Closures or lambda expressions have types which cannot be named. However, they implement special Fn, FnMut, and FnOnce traits:

fn apply_with_log(func: impl FnOnce(i32) -> i32, input: i32) -> i32 {
    println!("Calling function on {input}");
    func(input)
}

fn main() {
    let add_3 = |x| x + 3;
    let mul_5 = |x| x * 5;

    println!("add_3: {}", apply_with_log(add_3, 10));
    println!("mul_5: {}", apply_with_log(mul_5, 20));
}