I like matching on bools on the same cases where someone wouldn't write braces around the body in C: whenever the corresponding expressions keep you under the line length. For example:

    let plural = match cases.len() > 1 {
        true => "s",
        false => "",
    };

Of course, you'd more likely have something like

    let prefix = match cases.len() {
        0 => "no values".to_string(),
        1 => "a value".to_string(),
        n => format!("{} values", n),
    };