I'm -0.5 on this one, hurts readability. set() is strictly clearer than {}, which many people are going to guess creates a dict.

Will wait for comments of other maintainers, but inclined to close this one. Thanks though @rth

I am also -0. The curly braces have almost become synonymous with dicts. As far as I can see there is not much performance gain with this either (I couldn't detect any workhorse that needs optimization).

Thanks for the feedback. Yes, I agree that the {} notations for sets is somewhat confusing, still, that's the native way to define sets in Python (instead of set(<list>) which does some overhead iterations etc). CPython documentation for sets uses this notation. I feel part of the issue is that sets are generally little used (compared to dicts).

Closing, given your comments and the fact that all of these changes are indeed not in performance sensitive parts of the code.

Personally, I'm +1 on this--{'a', 'b'} it much cleaner than set(['a', 'b'])--but I'm not going to argue strongly for this PR now, since this is relatively minor cleanup. (But really, who can object to changing set([]) to set()?) I don't think we should object to the use of set literals in new code. The funny thing is, set literals will probably be more familiar to someone who learned Python six months ago than to someone who learned it six years ago.