From: David Kastrup <dak@gnu.org>
To: guile-user@gnu.org
Subject: Re: Multiple values passed as single argument to procedure
Date: Sun, 11 Jun 2017 10:28:38 +0200 [thread overview]
Message-ID: <87efur7wsp.fsf@fencepost.gnu.org> (raw)
In-Reply-To: 87mv9fnejc.fsf@gmail.com
Chris Marusich <cmmarusich@gmail.com> writes:
> I've noticed that when one passes multiple values as a single argument
> to a procedure, only the first value gets used. Is this expected?
Yes.
> However, I did find the following information in R6RS (Section 5.8:
> "Multiple return values"), which seems possibly relevant:
>
> "Not all continuations accept any number of values. For example, a
> continuation that accepts the argument to a procedure call is guaranteed
> to accept exactly one value. The effect of passing some other number of
> values to such a continuation is unspecified."
Guile resolves this unspecification by passing the first value. Here is
a proposal that tries normalizing the special case of passing zero
values as well:
<https://debbugs.gnu.org/cgi/bugreport.cgi?bug=17474>
This "use only the first value in non-multiple-value accepting contexts"
is similar to what Lua uses in the context of "..." argument lists.
--
David Kastrup
next prev parent reply other threads:[~2017-06-11 8:28 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-11 7:56 Multiple values passed as single argument to procedure Chris Marusich
2017-06-11 8:28 ` David Kastrup [this message]
2017-06-11 20:36 ` Mark H Weaver
2017-06-11 21:31 ` Mark H Weaver
2017-06-12 0:19 ` Chris Marusich
2017-06-12 4:25 ` Mark H Weaver
2017-06-12 8:19 ` Chris Marusich
2017-06-12 8:55 ` Neil Jerram
2017-06-12 9:48 ` Neil Jerram
2017-06-12 9:39 ` David Kastrup
2017-06-12 11:31 ` Mark H Weaver
2017-06-12 14:24 ` David Kastrup
2017-06-13 2:26 ` Mark H Weaver
2017-06-13 3:09 ` Mark H Weaver
2017-06-13 3:45 ` Mark H Weaver
2017-06-13 11:17 ` dsmich
2017-06-26 11:25 ` Alex Vong
-- strict thread matches above, loose matches on Subject: below --
2017-09-01 19:39 Chris Marusich
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