> From: Michael Sperber <xxxxxx@informatik.uni-tuebingen.de>

    Tom> Every function should take an extra parameter which
    Tom> represents the particular Scheme instance under
    Tom> consideration.  I might be running two different Scheme
    Tom> worlds in one process.

    > Can't you handle this implicitly? Or do you need to switch
    > between instances along a single call chain?

I'd prefer to be able to mix them, for example to be able to write
primitives which perform communication between them.

I think of them as comparable to the DISPLAY* parameters in Xlib.

It is a trade-off, I admit, between register pressure and fast/easy
access to instance-specific state.

-t