Hi All, I think Nathaniel had a good summary. My own 2ยข are mostly about the burden of supporting python2. I have only recently attempted to make changes in the C codebase of numpy and one of the reasons I found this more than a little daunting is the complex web of include files. In this respect, the python3/2 split is certainly not the biggest hindrance, but it was also not particularly helpful for understanding to have "translations" of python2 macros to python3 equivalents in npy_3kcompat.h: for newcomers, it would seem helpful if they could read the Python3 C-API and be able to understand what is going on. Of course, the above also proves Julian's point: for strings in particular, numpy still has a bit to go to be fully python3-ized. Finally, as for pypy: they just made a huge effort to become compatible with python3; is their plan really to stick with python2 much beyond 2020? All the best, Marten