map is lazy



examples/vectors/map-is-lazy/src/main.rs
fn main() {
    let numbers = vec![1, 3, 6];
    let double = numbers.into_iter().map(|num| { 
        println!("doubling {num}");
        num * 2
    });

    println!("Nothing happended yet");
    for num in double {
        println!("{num:?}");
    }
}

Nothing happended yet
doubling 1
2
doubling 3
6
doubling 6
12