sum for sequences?

Patrick Maupin pmaupin at
Tue Mar 30 04:31:44 CEST 2010

On Mar 29, 6:38 pm, Steven D'Aprano <st... at REMOVE-THIS-> wrote:
> With a very few exceptions (e.g. dict lookup being "usually" O(1), list
> append being amortized O(1)), Python makes no promises about performance.
> It's not part of the language. If you, the programmer, are making any
> assumptions about performance that aren't clearly and explicitly
> documented in the official docs, then YOU are at fault, not Python.

It's not about promises, guarantees, quid-pro-quo, etc.

It's about a lack of surprises.  Which, 99% of the time, Python excels
at.  This is why many of us program in Python.  This is why some of us
who would never use sum() on lists, EVEN IF IT WERE FIXED TO NOT BE SO
OBNOXIOUSLY SLOW, advocate that it, in fact, be fixed to not be so
obnoxiously slow.

BTW, it's also not about "fault".  There is no shame in writing a
Python program, seeing that it doesn't go fast enough, and then
hammering on it until it does.  There is also no shame in not reading
the docs before you write the program, although arguably (and you
obviously work very hard to help see to this) a great deal of shame
attaches to posting to the newsgroup before reading the docs.


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