Re: Feature suggestion: sum() ought to use a compensated summation algorithm

Szabolcs Horvát wrote:

Arnaud Delobelle wrote:

sum() works for any sequence of objects with an __add__ method, not
just floats! Your algorithm is specific to floats.

This occurred to me also, but then I tried

sum(['abc', 'efg'], '')

and it did not work. Or is this just a special exception to prevent the misuse of sum to join strings? (As I said, I'm only an occasional user.)

What you wrote is nonsensical there, no different from 'a' + 1 -- which is why it quite rightly raises a TypeError.

You're trying to add a list to a string, which is nonsensical. You add strings to strings, or lists to lists, but mixing them up doesn't make sense. Python can't guess what you mean when you write something like ['abc', 'def'] + '' -- which is the functional equivalent of your call to sum -- and so doesn't try. It indicates this by raising a TypeError.

--
Erik Max Francis && max@xxxxxxxxxxx && http://www.alcyone.com/max/
San Jose, CA, USA && 37 18 N 121 57 W && AIM, Y!M erikmaxfrancis
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