It would probably be better to port packages like Numpy to pure PyPy[0], but of course the CPython extensions compatibility layer is by itself important to incr

It would probably be better to port packages like Numpy to pure PyPy[0], but of course the CPython extensions compatibility layer is by itself important to increase the adoption of PyPy. The problem besides the jit not being able to inline external functions is that the CPython structures, and especially the refcounting used in CPython is problematic [1] [0]: Actually specifically numpy is being rewritten in PyPy as a RPython Mixed Module: http://doc.pypy.org/en/latest/extending.html#rpython-mixed-modules http://doc.pypy.org/en/latest/extending.html#rpython-mixed-m... [1]: http://doc.pypy.org/en/latest/discussion/rawrefcount.html http://doc.pypy.org/en/latest/discussion/rawrefcount.html