Proposal: [... for ... while cond(x)]

[Duncan Booth]

Eighty wrote:

> I suggest a new extension of the list comprehension syntax:
> 
> [x for x in xs while cond(x)]
> 
> which would be equivalent to
> 
> list(itertools.takewhile(cond, xs))
> 

What would this syntax offer that:

   [x for x in takewhile(cond, xs)]

doesn't currently offer? (Apart, that is, from saving you 3 characters of 
typing)