Procedural language implementation questions

[Sorry, my ISP managed to get itself on the RBL, so hub.org rejects my mail,
 and if I send mail to "hackers" mailing list from a different account, it
 gets rejected because that account isn't a subscriber to the list.  So, I'm
 sending this individually.]

I'm looking at implementing a procedural language for postgresql, and I
have a few questions I'd like to get feedback on before I start.

1.  First of all, is anybody already working on this?  I would like to
    avoid duplication of effort, if possible.

2.  Looking at the code, it seems that I basically need to do three things:
    write a parser (using gram.y as a model), implement code to handle flow-
    control nodes in the parse tree for the executor, and write a small bit of
    glue for a handler (starting with the stub in "man create_language").
    Is this basically correct?  Is there anything in these areas that is
    particularly fragile that I need to watch out for?

3.  I want to use Python as a model, because Python syntax is very simple,
    and the semantics are a very good fit with the postgres backend.  One
    problem I see, though, is that Python is dynamically typed, and looking
    at the backend code, it looks like postgres is statically typed.  If you
    have a Datum, there doesn't seem to be any way to know what's in it.
    Comments?  Suggestions?

Thanks.

    -Michael Robinson