Meaning:

    filter(False, lst)
    == (x for x in lst if not x)
    == itertools.filterfalse(None, lst)

I understand that it is a very minor enhancement, and with not much benefit. I just happened to think about it, and wondered why it didn't already exist. I figured it wouldn't hurt to put the idea out here.

(If anyone is interested, I was looking into ways that filter/map/itertools could "unwrap" each other at the C level to improve composition of generators, inspired by the functools.partial optimization.)

Do you mean like 'filter(None, lst)' does?

I don't think it is worth adding as a special case.  Itertools has it because of what itertools is (a mini-language for manipulating iterables), but the legacy filter function has no reason to grow additional special cases beyond None.  (It's not even clear why it has that one special case :)

ebarry, note that `filter(None, lst)` is equivalent to `filter(bool, lst)`, which is the opposite of `filterfalse(None, lst)`. (Though `filter(True, lst) == filter(bool, lst)` would be a parallel.)