“ArmanriazirustConceptbindingMatch” Ответ

ArmanriazirustConceptbindingMatch

//https://blog.rust-lang.org/2018/05/10/Rust-1.26.html#nicer-match-bindings
        // `self` has type `&List`, and `*self` has type `List`, matching on a
        // concrete type `T` is preferred over a match on a reference `&T`
        // after Rust 2018 you can use self here and tail (with no ref) below as well,
        // rust will infer &s and ref tail. 
//the compiler automatically references the Some, and since we're borrowing, name is bound as ref name automatically as well. If we were mutating:

fn hello(arg: &mut Option<String>) {
    match arg {
        Some(name) => name.push_str(", world"),
        None => (),
    }
}
//the compiler will automatically borrow by mutable reference, and name will be bound as ref mut too.