main.rs

fn main() {
    let x: Option<Result<(&str, &str), ()>> = Some(Ok(("x", "y")));
    // if let
    if let Some(Ok((a, _))) = x {
        if a == "x" {
            println!("a=x");
        }
    }
    // match
    match x {
        Some(Ok((a, _))) => {
            if a == "x" {
                println!("a=x");
            }
        }
        _ => {}
    }
}