All,
I hacked in support for OnlyWhen and \&Code from Algorithm::Loops. 
use v6;

sub NestedLoop (++@loop, +$OnlyWhen, +$code) returns Ref{
    my @pos = 0 xx (@loop.elems - 1), -1;
    return sub {
        my @group;
        loop {
            if ++@pos[-1] > @loop[-1].end {
                for reverse 0 .. @pos.end - 1 -> $i {
                    next if @pos[$i] == @loop[$i].end;
                    ++@pos[$i];
                    @pos = (@pos[0..$i], 0 xx (@pos.end - $i)) and las
+t;
                }
            }
            return () if @pos[-1] > @loop[-1].end;
            @group = map -> $i { @loop[$i][@pos[$i]] } 0 .. @pos.end;
            if $OnlyWhen.does(Code) { $OnlyWhen(@group) or next }
            $code(@group) if $code.does(Code);
            last;
        }
        return @group;
    };
};
my $next = NestedLoop(loop => ([0..2], [0..2], [0..2]));
my @group;
while @group = $next() { say ~@group; }

[download]
If anyone is having a hard time following my logic in order to come up with alternatives, ask and I will provide an explanation. The basic idea is counting where each position relates to an anonymous array and the base to count in for that position is dependent on that array.

Cheers - L~R

In reply to Re: Perl6 Contest #2: P6 That Doesn't Look Like P5 by Limbic~Region
in thread Perl6 Contest #2: P6 That Doesn't Look Like P5 by Limbic~Region

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