[Bob Ippolito]
Using the stack or not is an implementation detail, what matters is having more control over the flow of your programs in a reasonably efficient manner. It just so happens that the recursive evaluation in CPython uses the stack in such a way that makes these kind of constructs impossible, so it needed to be changed for Stackless.
Sorry Bob, you've reached my limit for repeating the same point over and over without making progress. You don't seem to be getting the real point of the responses you're getting, which are that Stackless is *not* a minor change to Python, and that it severely restricts the ways in which Python can interact with other systems, be they hardware platforms, software frameworks, or 3rd party extensions. Please step off your soapbox, listen, and understand how and why Stackless gets in the way of Python's range of applicability. --Guido van Rossum (home page: http://www.python.org/~guido/)