Is PyMC3 the precursor of PyMC? And PyMC4 the precursor of PYMC3?
If so, does this mean that PyMC4 will include all the functionality of PyMC and PyMC3?
Adding numbers to the package is a bit confusing.
Why haven’t you just released new versions of PyMC?
The API is very different between PyMC3 and PyMC due to the change of computation backend (from Fortran codes to theano). As the result, PyMC3 is not backward compatible with PyMC and released as a new package instead of a new version.
PyMC4 will aim to maintain much of the API of PyMC3, but since the backend changes again (to tensorflow), we think releasing it as a new package might be better.