my $prev = [];
@array = grep {
    my $i = 0;
    my $ret = 0;
    $ret = 1 if $#$prev != $#$_;
    while ($ret && $i <= $#$prev and $i <= $#$_){
        $ret = 1 if $prev->[$i] ne $_->[$i];
    }
    $ret;
} sort {
    my $i = 0;
    my $ret = 0;
    loop: while (1) {
        if ($i <= $#{$a} and $i <= $#{$b}){ # test if we still have something to compute
            $ret = $a->[$i] cmp $b->[$i]; # compute the difference of this element
            last loop if $ret; # if there's a difference return
            $i++;
        } else { # if the arrays are equal to this point in terms of elements, but not in length, we decide on the longer one
            $ret = $#{$a} <=> $#{$b}; # determine by length
            last loop;
        }
    }
    $ret;
} @array;