2016-01-07 13:14 GMT+01:00 Max Leske <maxleske@gmail.com>:

Very, very cool Sven (and Henrik!)!

And it even works with exotic objects: { 1@2. 2@3 } numbers sum ��> (3@5)��

I really not understand how it helps with original problem. There was example with colors sum which was stop people to allow sum on empty collection. How extra message solve it?