playground.org

fn main() {
    fn add1(n: i32) -> i32 {
        n + 1
    }
    let _add12 = |n: i32| n + 1;

    let o: Option<i32> = Some(2);
    let res = match o {
        None => None,
        Some(i) => Some(i + 1),
    };


    println!("res1 {:?}, res2: {:?}", res, res2);
}