Marc Feeley wrote:
> I repeat: in which implementations of
> Scheme will the multiple values API be faster than the equivalent pair
> of operations which return single values?

Ones in which the operation can be inlined by a compiler.

Of course inlining may be contrary to a strict reading of at least
R5RS, unless you're doing whole-program compilation, which further
reduces the value of standardizing these functions.

 > I find SRFI 77's complexity to be a real turn-off when I
> consider the changes required to implement it properly.  Surely I'm not
> the only implementer to feel this way.

You're not.

Though a tuned reference implementation that makes uses of a small
number of implementation-optimized primitives would help.  But
please note that in some implementations "efficient fixnums" may
mean unboxed C/C++/Java values rather than general Scheme values.
Some of us need to be able to classify at compile time whether
a name or expression is a boxed object or an unboxed native number.
Similar for floating point - that is even more common, I suspect.
--
	--Per Bothner
xxxxxx@bothner.com   http://per.bothner.com/