Those are excellent points. In the context of CPython, Guido van Rossum made the design decision to not use tagged objects, based on experience with ABC impleme

Those are excellent points. In the context of CPython, Guido van Rossum made the design decision to not use tagged objects, based on experience with ABC implementation, which did. See https://mail.python.org/pipermail/python-dev/2004-July/046147.html https://mail.python.org/pipermail/python-dev/2004-July/04614... . I just realized though that since the patch to support tagged integers is small, a closed system like the CCP Games distribution of Python, which has no extensions they don't control, might be able to use this idea.