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

[Mark H Harris]

On 3/28/14 9:45 PM, Chris Angelico wrote:
> On Sat, Mar 29, 2014 at 8:18 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
>> We have a unicode system [1] capable of zillions of characters, and most of
>> [us] have some qwerty system keyboard [104 keys?] with meta key mappings for
>> a few more. Talk about the cart before the horse.
>>
>> We need a standard input system not controlled by Microsoft...
>
> ... uhh... how does the QWERTY system demonstrate Microsoft's
> control?? There's more than a hundred years of gap between them, and
> in the wrong order.

    You know the answer to this question. Does your keyboard have the 
"Windows" emblem|logo on the meta key(s) on lower right, lower left? On 
a standard keyboard its the meta key between ctrl and alt.  Microsoft 
has controlled that meta section of the keyboard for years, effectively 
preventing those keys from being used for unicode meta control keys 
(ironical considering the fact the Microsoft is a major player at the 
unicode consortium).  The meta keyboard on the mac is much more of what 
I have in mind, but that's mac only for now.

> By the way, thanks for telling me what a zillion is. It must be 65536,
> because that's the biggest thing Unicode gives us plural of in number
> of characters. :)

    ha!  :-))   A zillion is 65536 x(several thousand languages). 
Actually I used a zillion because the consortium doesn't even put a 
number on it... because there is a difference between script and 
language, and there are many languages that use Latin. The point is its 
a huge number greater than 128 or 256. (or 104)
>
> Considering that we have ten fingers, having 1114112 keys would be
> quite impractical.

    don't be literal, think meta pages (key mappings) over the actual 
keyboard, but think "standards".

> Do you really want a keyboard that takes up that much space? Most
> people can't efficiently use F1 through F12, much less another hundred
> or two hundred keys.

    No, I want a standard unicode keyboard (a standard specification for 
a unicode keyboard) that facilitates unicode typing with minimal actual 
keys and standard key maps for alternate sets that may be easily 
selected without a mouse and without moving the hands from the home row.

    The mac does a pretty good job of this now, but the mapping editor 
is not built-in; otherwise, the key mappings are very good, quite easy, 
and very fast. But, like Steven pointed out, everyone needs to be on the 
same unicode input device (as standard) before language specs could 
relay on certain code points for tokens | identifiers.

marcus