# multiple values proposal

   From: Norman Adams <norman@parc.xerox.com>
Date: 	Sun, 17 May 1992 23:34:37 PDT

Here is the most recent proposal for multiple values that I could find.
-Norman

-----------------------------
%%% Multiple values compromise proposal of December 4, 1989.
%%% This is raw TeX.
\def\mvcall{call-with-values}
\def\mvcontinue{values}

The editors are directed to add text to R$^5$RS so as to include the
procedures {\tt \mvcontinue{}} and {\tt\mvcall{}} consistent with the
following definitions.  The {\tt \mvcontinue{}} procedure takes any
number of arguments, and simply passes them to its continuation.  The
{\tt\mvcall{}} procedure takes a thunk and a procedure, and calls the
thunk with a continuation that, when passed some values, calls the
procedure that was the second argument to the {\tt\mvcall{}} procedure
with those values as arguments.  Except for continuations created by
the {\tt\mvcall{}} procedure, all continuations take exactly one
value, as now; the effect of passing no value or more than one value
to continuations that were not created by the {\tt\mvcall{}} procedure
is unspecified (as indeed it is unspecified now).
Suggested formal semantics:
$$\hbox{\it \mvcontinue{}} = \lambda\epsilon^*\kappa . \kappa\epsilon^*$$
$$\hbox{\it \mvcall{}} = \hbox{\it twoarg }(\lambda \epsilon_1 \epsilon_2\kappa . \hbox{ \it applicate } \epsilon_1 \langle \rangle \lambda \epsilon^* . \hbox{ \it applicate } \epsilon_2 \epsilon^* \kappa)$$

\end

I would like this to be amended so that continuations which ignore the
returned value can also receive 0 values.  I am not sure how to word
this.  The advantage of doing this is that if an implementation
returns 0 values for procedures whose values are unspecified in the
standard, the implementation can catch as errors places where 0 values
are being stored.