Missing values

One should ask the question what happens if the list runs out of values in the middle, of a multi-value iteration? That is, what happens to the follow loop?

#!/usr/bin/perl6
use v6;

for (1, 2, 3, 4, 5) -> $x, $y {
	say "$x $y";
}

In this case Rakudo throws an exception when it finds out it does not have enough values for the last iteration. It will look like this, (with a bunch of trace information afterwards). 1 2 3 4 StopIteration In order to avoid the exception we could tell the loop that the second and subsequent values are optional by adding a question mark after the variable

#!/usr/bin/perl6
use v6;

for (1, 2, 3, 4, 5) -> $x, $y? {
	say "$x $y";
}

Unfortunately as of today this latter construct does not work yet.