> it shouldn't break fundamental rules of the language

it doesn't? you simply don't understand what a match statement is.

https://doc.rust-lang.org/book/ch19-03-pattern-syntax.html

    let num = Some(4);

    match num {
        Some(x) if x % 2 == 0 => println!("The number {x} is even"),
        Some(x) => println!("The number {x} is odd"),
        None => (),
    }

notice that x is bound to 4.