[plt-scheme] Proposal for s-expr tracing format

> John's suggestion has a certain appeal -- [...]

It's definitely a *cute* suggestion.  But it has appeal for no more
than a moment.

To accept this "solution" would be to agree that continuations are so
abnormal that programmers should never be able to work conveniently
with them.  That is, we would be expressly penalizing them: first
creating the incentive of being able to walk the trace using
s-expression walkers, then perversely taking it away by making the
parens not match and the walkers therefore no longer work.

I'm not sure I'd want to send out that message about continuations.
If anything, a TRACE done right could be a handy tool to
*understanding* continuations!  (Until the Stepper handles
continuations, that is, but I think that's slated for about 2025?)

Shriram