> The main emphasis was to show that there was a pattern unfolding that > should have been translated into more pythonic code than just > hard-coding nested loops.
Practicality beats purity. That you would solve a more general problem in a more general way doesn't mean that you shouldn't solve the more specific problem (combinations from three sets) in a specific, easy-to-read way. Readability counts. I find your solution (with nested generators) *very* unpythonic. It is much more complicated than necessary to solve the problem at hand, and it doesn't get Pythonic just by using the latest language features. It may be a smart solution, but not a Pythonic one. Regards, Martin P.S. To solve the general problem, I like http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/496807 -- http://mail.python.org/mailman/listinfo/python-list