Pre-RFC: Break with value in for/while loops

[pickfire]

@RustyYato

for × in iter { break 0 }; // <--- let x = 0; // any other expression

Wondering about the semicolon with a different approach, why not have something to void that?

for x in iter {
    dreak 0  // dreak could be anything or even break_raw
}  // <--

In the above case, dreak could made the for loop automatically get the inner value.

@dtolnay

break T; sufficiently clearly communicates from writer to reader that we care about the value of the enclosing loop expression. I think it is more valuable to be consistent about break T; breaking with a value than to be consistent about break (); being interchangeable with break; , which is theoretically attractive but not at all valuable to reading or writing code.

Or even using semicolon for control, nice idea but may be confusing to beginners at first.

Either way, I still think match follows by for loop seemed ugly and can be yet another iterator-like options.

match for x in iter { if x == 4 { break x } } {
    None => /* then */,
    Some(_) => /* else */,
}