I see nothing wrong with the *functionality* of the extension.
The problem is that it does not belong in catch proper,
since it messes up the typing, and makes catch unnecessarily
complicated. (A soft typing system for Guile would have to do
major kludging to deal with the extended catch.) If the
functionality is sufficiently useful to standardize, it would
be much cleaner to use a different two-argument function for this case:
(catch-unique (lambda (KEY) ... (throw KEY) ...) HANDLER)
But I don't think the functionality is that useful, and in any case
it can be easily simulated.
--Per Bothner
Cygnus Solutions bothner@cygnus.com http://www.cygnus.com/~bothner