multiple values

[will@cs.uoregon.edu]

Morry Katz:
    I can't imagine how one could create an implementation in which the arity
    information is not already present in some form for procedures that are
    passed as arguments.  Similarly, implicit continuations...

Passing an incorrect number of arguments to a procedure isn't required to
signal an error, so procedures don't have to check it.  Hence the arity may
not be retrievable through any amount of bit-twiddling.  Also, why should
the run-time representation of (lambda args #t) include any bits that
indicate the number of arguments it expects?  As a third example, the
variety and complexity of code sequences emitted by multiple compilers
may make the arity unrecoverable when embedded within code.  Similarly
for continuations.

That said, I don't think ACCEPTS? would be an unreasonable burden on any
implementor.  But it's certainly a burden that doesn't exist now.

Chris Hanson:
    I agree, with Norman, that the proposed functionality is useful in the
    absence of `accepts?'.

I agree with Chris and Norman.

Chris Hanson:
    ...multiple values have usefulness independent of the "truncation"
    feature, and I feel they are worth having anyway.

I agree again.  I believe the multiple values proposal being considered
allows the "truncation" feature as an extension: the critical property
is that (VALUES E) is always equivalent to E.

Peace, Will