Python 3 added type annotations, but I've yet to see much interest in actually using it. Traits (http://code.enthought.com/projects/traits/ http://code.enthoug

Python 3 added type annotations, but I've yet to see much interest in actually using it. Traits (http://code.enthought.com/projects/traits/ http://code.enthought.com/projects/traits/) pursues the error-checking side of type declarations, while Cython pursues the speed side. If you want both then too bad ;)