Re: [Scheme-reports] multiple values module

[Eli Barzilay <eli@x>]

About a minute ago, John Cowan wrote:
> Eli Barzilay scripsit:
> 
> > If you're talking about such things as
> > 
> >   (define-values (getter setter)
> >     (let ([state #f])
> >       (values ...blah1...
> >               ...blah2...)))
> 
> I'm not only not talking about such a thing, I don't even understand
> it.

It is a very common reason for having multiple values.


> What I meant was this: trivially any procedure that returns
> multiple values could as well return a single value which is an
> aggregate of some sort such as a list or general vector.  However,
> it costs something to aggregate and disaggregate this value, a cost
> which *some* implementations of multiple values need not pay.

You can't avoid the extra cost.  Implementations vary with heap or
stack allocation which is something that goes in a different level.
In any case, your original statement of multiple values as some
lightweight alternative is even more wrong given this.  (The
historical context is first class continuations.)

-- 
          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
                    http://barzilay.org/                   Maze is Life!

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