See the Wikipedia article on modular exponentiation. Basically, when you do a**d % n, you actually have to calculate a**d, which could be quite large. But there are ways of computing a**d % n without having to compute a**d itself, and that is what pow does. The ** operator can’t do this because it can’t … Read more
If you want to determine whether a value is exactly True (not just a true-like value), is there any reason to use if foo == True rather than if foo is True? If you want to make sure that foo really is a boolean and of value True, use the is operator. Otherwise, if the … Read more
PyPy is not a fork of CPython, so it could never be merged directly into CPython. Theoretically the Python community could universally adopt PyPy, PyPy could be made the reference implementation, and CPython could be discontinued. However, PyPy has its own weaknesses: CPython is easy to integrate with Python modules written in C, which is … Read more
“PyPy is a reimplementation of Python in Python” is a rather misleading way to describe PyPy, IMHO, although it’s technically true. There are two major parts of PyPy. The translation framework The interpreter The translation framework is a compiler. It compiles RPython code down to C (or other targets), automatically adding in aspects such as … Read more
NOTE: PyPy is more mature and better supported now than it was in 2013, when this question was asked. Avoid drawing conclusions from out-of-date information. PyPy, as others have been quick to mention, has tenuous support for C extensions. It has support, but typically at slower-than-Python speeds and it’s iffy at best. Hence a lot … Read more