Re: [Chicken-hackers] [PATCH] R7RS delay/force/delay-force

[John Cowan]

"Jörg F. Wittenberger" scripsit:

> Sure it's easy to convert multiple value returns into a single value
> (e.g. a list) and back. Scheme _could_ be done without multiple
> values at all (the way you describe).  Just: multiple values are
> useful as an alternative to "(one shot) objects" and _may_ be
> implemented more efficient.

Yes, they may be when returned directly, but not when cached for later
return.  In that case, allocating a data structure (even if it's
never used again) is unavoidable.

> Maybe even declare "at least threads" should do "the right thing and
> block" (if nobody can come up with a trick to handle call/cc too.

Threads are not defined in R7RS-small, and the only place we discuss them
is in `parameterize`, where we explain that a value dynamically bound in
one thread does not affect any other threads (a bare minimum requirement).
Note that R7RS parameters can be rebound but can't be mutated, which was
done specifically because some implementations copy the mutated value
when forking a new thread and others do not.

-- 
John Cowan          http://www.ccil.org/~cowan        address@hidden
To say that Bilbo's breath was taken away is no description at all.  There are
no words left to express his staggerment, since Men changed the language that
they learned of elves in the days when all the world was wonderful. --The Hobbit