Explanation of this Python language feature? [x for x in x for x in x] (to flatten a nested list)

[Ian Kelly]

On Fri, Apr 4, 2014 at 10:10 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> On 4/4/14 6:16 PM, Mark Lawrence wrote:
>>
>> Fear/panic of a fork, where did that come from?  It's certainly the
>> first I've ever heard of it.
>>
>
> hi Mark, it came from Ian; or, my interpretation of Ian. It comes out on the
> net too (from various places). Here is Ian's quote, then my comment:
>
>
>> Eventually users still on 2.x will need to upgrade, but you
>> can't force them to do it on your own schedule.  That path will just
>> end up driving them to another language, or to a fork of 2.7.
>
>
> The sentiment behind this last quote is essentially fear (and that is
> natural). Its basically the tension between (I'm speaking as the royal we
> here) we don't want folks to be driven away from Cpython as a language, and
> we don't want them to fork the Cpython interpreter, so we'll take a very
> casual and methodically conservative approach to nudging people towards a
> Cpython3 migration route ( I am speaking not for the community, just
> hypothetically trying to get at the gist of Ian's quote);  please forgive me
> if I didn't quite get it.

A fork is undesirable because it fragments the community.  I don't
think "fear" or "panic" are the right words for it.