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Re: (+ (values 1 2)) should be 1
From: |
Andy Wingo |
Subject: |
Re: (+ (values 1 2)) should be 1 |
Date: |
Tue, 24 May 2011 15:11:19 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.2 (gnu/linux) |
On Tue 24 May 2011 12:35, Hans Aberg <address@hidden> writes:
> On 23 May 2011, at 15:49, Andy Wingo wrote:
>
>>>> But, it is 1 and 2, currently. (+ FOO) inlines just to FOO, too
>>>> optimistically.
>>>
>>> It is unspecified according to rsr5.
>>
>> I know. I'm talking about Guile here.
>
> The Guile manual, sec. 10.2.5.2, says that SCM_UNSPECIFIED is to be used when
> the Scheme standard says the return is an unspecified value.
>
> So this Lisp extension breaks off from that. If one wants it, perhaps, there
> should be some way to invoke it.
Hans, you are misreading. (+ 1) is 1 according to the R5RS. (+ "foo")
is an error. (+ (values 1 2)) is unspecified, as an instance of
returning an unexpected number of values to a continuation, but it is
not an instance of the unspecified value.
When a continuation that expects one value receives more values than it
is expecting -- e.g., the <> in (+ <>) expects one value -- Guile
truncates those values to the first one. If such a continuation
receives 0 values, Guile signals an error.
Andy
--
http://wingolog.org/
- (+ (values 1 2)) should be 1, Andy Wingo, 2011/05/22
- Re: (+ (values 1 2)) should be 1, Hans Aberg, 2011/05/23
- Re: (+ (values 1 2)) should be 1, Andy Wingo, 2011/05/23
- Re: (+ (values 1 2)) should be 1, Hans Aberg, 2011/05/23
- Re: (+ (values 1 2)) should be 1, Hans Aberg, 2011/05/24
- Re: (+ (values 1 2)) should be 1,
Andy Wingo <=
- Re: (+ (values 1 2)) should be 1, Hans Aberg, 2011/05/24
- Re: (+ (values 1 2)) should be 1, Andy Wingo, 2011/05/24
- Re: (+ (values 1 2)) should be 1, Hans Aberg, 2011/05/24
- Re: (+ (values 1 2)) should be 1, Mark H Weaver, 2011/05/24
- Re: (+ (values 1 2)) should be 1, Hans Aberg, 2011/05/25
- Re: (+ (values 1 2)) should be 1, Mark H Weaver, 2011/05/25
- Re: (+ (values 1 2)) should be 1, Hans Aberg, 2011/05/25