On Mon, Oct 17, 2016 at 10:32 AM, Steven D'Aprano <st...@pearwood.info> wrote:
> But if we *do* accept this syntax, then I believe that we should drop > the pretense that it is a natural extension of sequence unpacking in the > context of a for-loop-with-append (i.e. list comprehensions) and accept > that it will be seen by people as a magical "flatten" operator. [...] > So, yet again for emphasis: I see what you mean about unrolling the list > comprehension into a list display. But I believe that's not a helpful > way to think about list comprehensions. Moreover, this "magical flatten" operator will crash in bad ways that a regular flatten() will not. I.e. this is fine (if strange): >>> three_inf = (count(), count(), count()) >>> comp = (x for x in flatten(three_inf)) >>> next(comp) 0 >>> next(comp) 1 It's hard to see how that won't blow up under the new syntax (i.e. generally for all infinite sequences). Try running this, for example: >>> a, *b = count() Syntactically valid... but doesn't terminate. -- Keeping medicines from the bloodstreams of the sick; food from the bellies of the hungry; books from the hands of the uneducated; technology from the underdeveloped; and putting advocates of freedom in prisons. Intellectual property is to the 21st century what the slave trade was to the 16th.
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