sub signatures coming

[Matt Lawrence]

On 25/02/14 11:18, James Laver wrote:
> On 25 Feb 2014, at 03:45, Paul Makepeace <paulm at paulm.com> wrote:
>
>> On Mon, Feb 24, 2014 at 2:04 PM, Steve Mynott <steve.mynott at gmail.com> wrote:
>>> http://perltricks.com/article/72/2014/2/24/Perl-levels-up-with-native-subroutine-signatures
>> Finally. But don't believe the python/perl comparison troll, as
>> python, for once, actually outguns perl on a character chomping basis,
>>
>> sub pairwise_sum ($arg1, $arg2) {
>>     return map { $arg1->[$_] + $arg2->[$_] } 0 .. $#$arg1;
>> }
>>
>> def pairwise_sum(list1, list2):
>>     return [i + j for i, j in zip(list1, list2)]
>>
>> Paul
> But I probably already have List::MoreUtils imported (because Perl).
>
> sub pairwise_sum ($a1, $a2) {
>    zip @$a1, @$a2;
> }
>
> And lets ignore the fact that the perl version that was used in the article was buggy. If $arg2 is shorter than $arg1 it breaks. zip’s supposed defined behaviour is to stop when either list runs out of elements.

Whereas this one is buggy because it doesn't actually do what it says on 
the tin. Where's the summation?

Matt