[Python-Dev] dict comps

[Tim Peters]

[M.-A. Lemburg]
> ...
> Seriously, this goes down the path of lazy evaluation of expressions.

Lazy sequences specifically, but that's been a tension in Python all along
(it started with the for/__getitem__ protocol, and nothing we do from here
on in will ever be as much of a hack as xrange() was for that <0.9 wink>).

> Not sure whether this is the right path to follow though (can cause
> brain damage due to overloaded builtin debuggers, IMHO).

We can introduce "L[...]" for explicitly lazy list comprehenions <wink>.

> BTW, looks like I can finally get rid off the dict() builtin I
> have in mxTools which is Good News !

It's not quite the same in the details:  CVS dictionary(s) works just like
CVS

    d = {}
    for k, v in s:
        d[k] = v

In particular, it demands that the elements of s each produce exactly 2
objects, where IIRC the mxTools dict() requires at least 2 (ignoring any
after the second).  Was ignoring excess objects "a feature", or just
exposing an implementation that didn't want to bother to check?