Optional type checking for Python

Dear All,

(I'm forwarding this from the main pydev mailing list)

I'm a Master's student at Imperial College London currently selecting
a Master's thesis subject. I am exploring the possibility of "optional
typing" and "pluggable type systems" (Bracha) for Python. Reading
around I see that the closest we ever got was PEP 246 (object
adaption) which has been dropped in favour of generic functions.

Guido informs me optional static typing probably won't appear in
Python 3 so I'm safe exploring the ideas for my thesis. I'm planning
on making the project quite research based and explore implementations
in CPython or Jython.

Does anyone have any thoughts about the project? Useful background
reading, ideas, flames etc?

Thanks,
Neil Dunn