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Stdle #81 · option · 2026-08-26

What does this Rust snippet output?

A past puzzle — fully playable. 4 attempts, hints on wrong guesses.

fn main() {
    let x = Some(5);
    let r = x.map_or_else(|| -1, |n| n + 1);
    println!("{}", r);
    let y: Option<i32> = None;
    println!("{}", y.map_or_else(|| -1, |n| n + 1));
}
Option
2 lines
4 attempts left

Answer & explanation