pypy IS compatible with C extensions, via what we call "cpyext": https://doc.pypy.org/en/latest/faq.html#do-c-extension-modules-work-with-pypy https://doc.pypy.

pypy IS compatible with C extensions, via what we call "cpyext": https://doc.pypy.org/en/latest/faq.html#do-c-extension-modules-work-with-pypy https://doc.pypy.org/en/latest/faq.html#do-c-extension-modul... The problem of cpyext is that it's super slow, for good reasons: https://pypy.org/posts/2018/09/inside-cpyext-why-emulating-cpython-c-8083064623681286567.html https://pypy.org/posts/2018/09/inside-cpyext-why-emulating-c... There are efforts to create a new C API which is more friendly to alternative implementations (including CPython itself, when they want to change how they do things internally): https://hpyproject.org/ https://hpyproject.org/ https://github.com/py-ni https://github.com/py-ni