In practice, it's quite a useful feature, because you can write things like this:

    let day_number = match name {
        "Sunday" => 0,
        "Monday" => 1,
        "Tuesday" => 2,
        "Wednesday" => 3,
        "Thursday" => 4,
        "Friday" => 5,
        "Saturday" => 6,
        _ => return Err("invalid day")
    };