Perl Myths Talk 2009(slideshare.net)

    sub bottom_up_tree {
        my($depth) = @_;
    
        my @pool;
        push @pool, [undef, undef, -$_] foreach 0..2**$depth-1;
    
        foreach my $exponent (reverse(0..($depth-1))) {
            push @pool, [reverse(splice(@pool, 0, 2)), $_]
                           foreach reverse(-(2**$exponent-1) .. 0);
        }
        return $pool[0];
    }

    xs = [5, 6]
    xs.append(7)
    print xs[2]     # prints 7
    xs.append([])   # easy to append lists to other lists
    xs[3].append(6) # easy to append to the inner list
    some_func(12, "hello", xs, True) # easy to pass to a function

    $xs = [5, 6];       # must be a reference
    push @$xs, 7        # deference $xs as a list
    print "$xs->[2]\n"  # still not too bad
    push @$xs, []       # add a nested list reference
    push @{$xs->[3]}, 6 # omgwtf?!
    some_func(12, "hello", $xs, 1) # not too bad