[Types-sig] Proposed Goals PEP

[Guido van Rossum]

> I'll consider your idea. I've seen it before (under various syntaxes and
> names) and I can certainly see it's strengths. I have to think carefully
> before I throw away any hope of ever statically typing these things so
> decisively. Once you depend on .check methods (called "implementedBy" in
> the scarecrow interfaces model) you have made static type checking
> equivalent to the halting problem! It is one thing to not go far out of
> your way to help static type checkers (which is what I tried to do in
> the past) and another to actively get in their way!
> 
> Still, I'm thinking about it...it does have a certain simplicity. I
> think that it will probably be a basis at least for experimentation and
> maybe for the final PEP.

Note that he was also proposing a syntax that does not necessarily
depend on .check() methods!

--Guido van Rossum (home page: http://www.python.org/~guido/)