my @lists = (
    [1,2,6],
    [4,5],
    [7,3],
);

# Init indexes to zero
my @idx = map { 0 } (0..$#lists);

my $n = 0;

COMP:
while (1) {
    $n++;
    print "comp[$n] = [";
    # Join all list elements given by index array
    print join ',', map { $lists[$_][$idx[$_]] } (0..$#lists);
    print "]\n";

    # Increment lowest index, handle overrun
    INDEX:
    foreach my $i (0..$#lists) {
       $idx[$i]++;
       # If new index greater then highest index
       if ($idx[$i] > $#{$lists[$i]}) {
           # Wrap around
           $idx[$i] = 0;
           if ($i == $#lists) {
               # Stop outher loop if last index overruns
               last COMP;
           }
       }
       else {
           # stop if no overrun occured
           last INDEX;
       }
   }
}

__END__
comp[1] = [1,4,7]
comp[2] = [2,4,7]
comp[3] = [6,4,7]
comp[4] = [1,5,7]
comp[5] = [2,5,7]
comp[6] = [6,5,7]
comp[7] = [1,4,3]
comp[8] = [2,4,3]
comp[9] = [6,4,3]
comp[10] = [1,5,3]
comp[11] = [2,5,3]
comp[12] = [6,5,3]

##</code><code>##

22a23
>        $i = $#lists - $i;
28c29
<            if ($i == $#lists) {
---
>            if ($i == 0) {