restriction on sum: intentional bug?

Aahz aahz at
Sun Oct 18 00:34:14 CEST 2009

In article <a33fb576-f453-4936-8551-9b999b5e2927 at>,
Mark Dickinson  <dickinsm at> wrote:
>On Oct 17, 9:49=A0pm, a... at (Aahz) wrote:
>> Ahhh, I vaguely remember there being some discussion of this when sum()
>> was introduced -- I think that using InPlaceAdd would have caused bad
>> behavior when the initial list was referred to by multiple names.
>Thanks for the pointer: I've now found the thread.  It looks like
>Alex Martelli made this exact change 6 years ago, and then had to
>revert it because it changed behaviour:
>I've just checked in an extra test to to make sure
>this bright idea isn't repeated. :)

Thanks!  I hope you added a comment to the code, too.  ;-)

And wow, sometimes my memory amazes me...
Aahz (aahz at           <*>

"To me vi is Zen.  To use vi is to practice zen.  Every command is a
koan.  Profound to the user, unintelligible to the uninitiated.  You
discover truth everytime you use it."  --reddy at

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