Mypy will support accessing Python modules from mypy programs, running in the stock CPython virtual machine for the best compatibility. You can also access your existing Python code.
Cython, not CPython. I took it as a given that it will run "pure" CPython-compatible code. I meant that the ability to JIT down Cython code (without the C translation step) would be a strong hook to get some people interested. There have been steps toward this in PyPy, and I expect it will happen in Numba sooner or later.
This would actually be even more compelling that I initially thought, since you pointed out that mypy run in stock CPython (I overlooked that and assumed it would have separate interpreter). All hypothetical, of course -- where's the github link?
Access to Python libs
Mypy will support accessing Python modules from mypy programs, running in the stock CPython virtual machine for the best compatibility. You can also access your existing Python code.