[Python-ideas] Proposal: A Reduce-Map Comprehension and a "last" builtin

[Jacco van Dorp]

> With the increased emphasis on iterators and generators in Python 3.x,
> the lack of a simple expression level equivalent to "for item in
> iterable: pass" is occasionally irritating, especially when
> demonstrating behaviour at the interactive prompt.

I've sometimes thought that exhaust(iterator) or iterator.exhaust() would be
a good thing to have - I've often wrote code doing basically "call this function
for every element in this container, and idc about return values", but find
myself using a list comprehension instead of generator. I guess it's such an
edge case that exhaust(iterator) as builtin would be overkill (but perhaps
itertools could have it ?), and most people don't pass around iterators, so
(f(x) for x in y).exhaust() might not look natural to most people. It
could return
the value for the last() semantics, but I think exhaustion would often be more
important than the last value.

2018-04-09 0:58 GMT+02:00 Greg Ewing <greg.ewing at canterbury.ac.nz>:
> Kyle Lahnakoski wrote:
>
>> Consider Serhiy Storchaka's elegant solution, which I reformatted for
>> readability
>>
>>> smooth_signal = [
>>>     average
>>>    for average in [0]
>>>    for x in signal
>>>     for average in [(1-decay)*average + decay*x]
>>> ]
>
>
> "Elegant" isn't the word I would use, more like "clever".
> Rather too clever, IMO -- it took me some head scratching
> to figure out how it does what it does.
>
> And it would have taken even more head scratching, except
> there's a clue as to *what* it's supposed to be doing:
> the fact that it's assigned to something called
> "smooth_signal" -- one of those "inaccurate names" that
> you disparage so much. :-)
>
> --
> Greg
>
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