Hi Matti. I'm happy to see that you're doing community outreach. I haven't tried PyPy in a while. The general impression I have about PyPy is that as soon as you try to do anything a little bit complicated, things break in unexpected ways and there's little support. Also, I love using Wing IDE for debugging, and if I'm not mistaken it can't debug PyPy code.

I'm currently doing multi-agent reinforcement learning research using RLlib, which is part of Ray. I tried to install a PyPy environment for it. It failed because Ray doesn't provide a wheel for it:

    Could not find a version that satisfies the requirement ray (from versions: none)

My hunch is that even Ray did provide that, there would have been some other roadblock that would have prevented me from using PyPy.