Steven D'Aprano wrote:
> On Sat, 06 Sep 2008 00:33:25 -0400, Manu Hack wrote:
>
>> Actually it's even more natural to state sum([x]) = x, and this way you
>> can never conclude that sum([]) = 0 from there.
>
> But what you can say is that for any list L, sum(L) = sum(L + [0]).
>
> Therefore sum([]) = sum([] +[0]) = 0
Yep. The way it is preserves the distributive property
sum(a+b) = sum(a) + sum(b)
This would matter in cases like (untested code..)
suvsales = sum (sum (s.price for s in d.sales if s.class='suv') for d in
districts)
Mel.
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