PyPy has its own implementation of the sqlite module based on CFFI, as well as other stdlib modules that wrap C libraries (a lot of the libraries written in C f

PyPy has its own implementation of the sqlite module based on CFFI, as well as other stdlib modules that wrap C libraries (a lot of the libraries written in C for the sake of performance in CPython are just pure Python in PyPy — CPython normally includes both pure Python and not in those cases). numpy is far more complex because it's a far bigger API than anything like sqlite, though work is progressing on it.