Well, it won't take much to have tools like Numba (http://numba.pydata.org/ http://numba.pydata.org/) taking advantage of such "type info" during optimization p

Well, it won't take much to have tools like Numba (http://numba.pydata.org/ http://numba.pydata.org/) taking advantage of such "type info" during optimization phase. On the other hand IDEs are already taking advance of those (see PyCharm). And by the way the future looks bright as interesting PEPs are coming: PEP509, PEP510 (https://www.python.org/dev/peps/pep-0510/ https://www.python.org/dev/peps/pep-0510/) and PEP511 for instance.