I just downloaded PyCharm to use the 30 day trial; I specifically wanted to test its claimed Vim emulation plugins.

My first impression is that it's the standard, ugly Java IDE, but more importantly, it's awfully slow. Loading a small, five file project from a Github repository took me almost ten minutes to get to the point where the UI was done doing things and would actually respond to me in a reasonable time frame. But even after that point, just about every action, like opening files or even just browsing the window menus, is an exercise in waiting for the UI to catch up with what I'm asking it to do, and there's never any indication that it's actually doing something when I tell it to. I'm left just wondering if I need to try clicking again, or if I'm just being too impatient. I haven't even tried to edit an actual file yet, and I'm already frustrated by the software...

After reading this I looked and saw that PyCharm is on special for $49, which falls into my compulsive purchase zone! (I also have the significant remains of a 1 lb bag of bay leaves in my fridge which I ordered from Amazon under similar compulsive circumstances. That's a lot of bay leaves.)

We're veering off-topic here, but why did you buy so many bay leaves?

I cook a lot and I was tired of running out and paying $5 for a jar of about 10 broken leaves. So I got a bag of organic turkish bay leaves from amazon for only $18. There must be at least 1000 leaves in the bag, which I'll leave to my children in my will one day. I'll drop the thread at this point, because I'm sure no one wants to hear more about my bay leaf glut.

Hm, cool. They must be doing some internal type inference, insofar that's at all possible, then, in order to add such refactoring features.

Thanks for pointing it out!

How does it work for you in practice? E.g. does it help you what operations are possible on a function argument? (inside the function definition, I mean)

PyCharm is produced by the same guys who created Resharper and a lot of other great tools like PHPStorm and TeamCity. Been using PHPStorm for nearly a year now, and I still find new things it can do.