#[derive(Debug)]
enum SoI {
    S(String),
    I(i32),
}

fn main() {

    let s = SoI::S(String::from("one"));


    // why this ?

    match s {
        SoI::S(ref x)  if x == "one" => {  println!("one") },
        _ => println!("not one"),
    }


    // if it can be done like this?

    match s {
        SoI::S(ref x)   => if x == "one" {  println!("one"); },
        _ => println!("not one"),
    }

}





// which is more preferable??