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

[Marko Rauhamaa]

Ian Kelly <ian.g.kelly at gmail.com>:

> You can get the desired effect by adding a layer of indirection:
>
>>>> fl = [(lambda x: lambda y: x+y)(x) for x in [1,2,3]]

A trick to remember! Variable lifetime reduction by function invocation.


Marko