[R6RS] Safe/unsafe mode

[dyb at cs.indiana.edu]

Ack, more unsupported claims.

> > Since the only purpose for using unsafe code is to increase efficiency, I
> > imagine I wouldn't be the only one upset to learn that unsafe declarations
> > effectively disable some optimizations.
>
> Well, that's going to be the case with any proposal
> that has been advanced so far, and with any I can
> conceive.

I don't believe this is true.  Can you describe an optimization that can
be done on code that is entirely safe that cannot be done on code
containing unsafe declarations in my model?

> Kent's preferred semantics, which I call Proposal 3,
> inserts the largest number of boundary crossings

Would you care to prove this claim?  I don't see why this is necessarily
the case or will even typically be the case in practice.

Kent