Taylor R Campbell scripsit:

> Not true: it is found in MIT Scheme, and used nontrivially there.

*sigh*  I need to keep firmly in mind that MIT Scheme documentation
isn't authoritative.  Thanks.  I'll add it.

> I don't understand your objection to SET-EPHEMERON-DATUM!, by the way.
> A concurrent GC needs to handle racing mutation by the mutator anyway.

Be that as it may (and my meaning is that proper ephemeron support already
adds an additional layer of complexity to the GC without piling Ossa on
Pelion), we have plenty of precedent for standardizing the intersection
of implementations.  Is there any benefit to mutable ephemerons over
ephemerons holding mutable boxes, if you are careful to ensure that the
object is never referred to outside its box except transiently?
If so, I'm not seeing it, but I am "only an egg" in ephemeron matters.

--
John Cowan          http://www.ccil.org/~cowan        xxxxxx@ccil.org
I amar prestar aen, han mathon ne nen,    http://www.ccil.org/~cowan
han mathon ne chae, a han noston ne 'wilith.  --Galadriel, LOTR:FOTR