Along the lines of what others have said: pprint() cannot consume an unknown iterator.
Perhaps so. It's nice to have printing be free of side-effects (other than the actual printing). I've been working with 3.0 daily for several months (on a book project) and mostly think it's great. But sooner or later, we're going to have to address the issue about iterator reprs at the interactive prompt. This is a separate and more general issue than pprint(). My experience so far is that it is that the shift to more things being unviewable at the prompt is bit frustrating and makes the language more opaque. If that has been a source of irritation to me, then it will likely be more acutely felt by people who are starting out and are using the interactive prompt to explore the language. I don't know the right answer here (perhaps an alternate sys.displayhook). Just wanted to provide some early feedback based on my experiences heavily exercising 3.0. Raymond P.S. My other experience with 3.0 is that my most frequent error has changed. It used to be that the number reason for my getting a syntax error was leaving-off a colon. Now, my number one reason is omitting parens in a print() function call. I thought I would get used to it quickly, but it still comes up several times a day.