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

[Mark H Harris]

On 3/24/14 8:45 PM, Steven D'Aprano wrote:

> Your insistence that lambda is confusing is awfully condescending. People
> are not as dumb as you insist, and they are perfectly capable of learning
> lambda without a comp sci degree. Like any technical jargon, there is
> vocabulary and meaning to learn, but the concept is no more difficult
> than ordinary def functions.

This is an Ad Hominem. My opinion that lambda is confusing must not be 
construed to mean condescension; not coming from my pen.

I do not insist that people are dumb, nor do I insist that people cannot 
learn python without a comp sci degree. Pushing those words into my 
mouth and then beating me up for saying them is, well, ad hominem.

What I am insisting is that *many* people, as point of fact, are 
confused by the python lambda construct particularly when it is embedded 
within a   for x in   and the lambda is supposed to capture the value x 
(as in my previous examples). This say nothing of their intelligence and 
says nothing about my supposed motive of condescension. (we my judge 
actions, but not motives)

I am advocating for understanding, among all python users--- novice and 
expert alike. Especially when I find so many experts who want to "know" 
(like the OP on this thread) and other experts who (like ecumenical 
councils) cannot agree (also noticed on this thread).

I am not seeking over simplification, and I am not seeking to limit the 
expert in any way;  just advocating for Aristotle's mean, whereat we 
find virtue.

marcus