Chapter 17.3 DSL: Curly braces in macro invocation

[Feliksas]

in this code snippet

macro_rules! calculate {
    (eval $e:expr) => {
        {
            let val: usize = $e; // Force types to be unsigned integers
            println!("{} = {}", stringify!{$e}, val);
        }
    };
}

what is the implication of using curly braces with stringify! ? Looks like those do not change program behaviour in any way, compared to normal parentheses.

[Kivooeo]

You can use any braces for macros, there is no actual difference

fn main() {
    let v = vec!(1,2,3);
    let v = vec!{1,2,3};
    let v = vec![1,2,3];
}

I'm not sure if we explaning this somewhere, and I also dont know why, just randomly found this

Does it worth mentioning?

[Feliksas]

probably worth mentioning, since it creates an impression of some kind of special case or implied special meaning in the current context