That is why I chose $a and $b, because of the sort magic.

I did consider setting $_ to a 2 element anonymous array, then you'd use it like this.

  scalarmap { $_->[0] + $_->[1] } 0, @z;
[download]

But that isn't as elegant.

I considered using $a and $_ but that offended me too!

I see from merlyn's post below that the maker of List::Util::reduce came to the same conclusions...