Ram Rachum wrote:
I noticed that `sum` tries to add zero to your iterable. Why? Why not just skip adding any start value if none is specified?
This current behavior is preventing me from using `sum` to add up a bunch of non-number objects.
Sometimes you might find that the list you're summing is empty. Because 'sum' is most often used with numbers, the default sum of a list is 0. If you want to sum a list of non-numbers, provide a suitable start value. For example, to sum a list of lists a suitable start value is []:
sum([[0, 1], [2, 3]], []) [0, 1, 2, 3]
I agree that it would be nice if the start value could just be omitted, but then what should 'sum' return if the list is empty? If sum([1, 2]) returned 3, then I'd want sum([]) to return 0. If sum([[1], [2]]) returned [1, 2], then I'd want sum([]) to return []. Unfortunately, I can't have it both ways.