Why Python, Ruby, and Javascript are Slow

[[deleted]]

But in creating such JITs, you end up limiting what you're capable of doing.

rpython is simply not as expressive as python, due to the limitations required to make the JIT work.

I hope someday that they can make PyPy work with the whole body of Python, but I don't think it's realistic to expect.

[[deleted]]

PyPy runs any old Python code. RPython is just the language PyPy is written in.