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Re: A value for "nothing"
From: |
John Cowan |
Subject: |
Re: A value for "nothing" |
Date: |
Tue, 28 Aug 2018 11:19:06 -0400 |
On Tue, Aug 28, 2018 at 3:01 AM Mark H Weaver <address@hidden> wrote:
> In RnRS, (define a (if #f #f)) is allowed and guaranteed to assign
> *some* object to 'a' without signalling an error.
Actually, the phrase used is "the result is unspecified", which
unfortunately
is not defined in any RnRS. Racket produces a syntax error in this
situation
at least in its default language.
> However, it's not
> specified what object will be assigned. It could be 2 or (foo bar) or
> "the cow jumps over the moon".
>
In practice, it is #t, #f, (), or a unique unspecified object across all the
Schemes I have tested, most often the last.
--
John Cowan http://vrici.lojban.org/~cowan address@hidden
LEAR: Dost thou call me fool, boy?
FOOL: All thy other titles thou hast given away:
That thou wast born with.
- Re: A value for "nothing", (continued)
- Re: A value for "nothing", Mark H Weaver, 2018/08/26
- Re: A value for "nothing", Matt Wette, 2018/08/26
- Re: A value for "nothing", tomas, 2018/08/27
- Re: A value for "nothing", Mark H Weaver, 2018/08/27
- Re: A value for "nothing", Hans Ã…berg, 2018/08/27
- Re: A value for "nothing", Mark H Weaver, 2018/08/27
- Re: A value for "nothing", Matt Wette, 2018/08/27
- Re: A value for "nothing", Mark H Weaver, 2018/08/28
- Re: A value for "nothing",
John Cowan <=
- Re: A value for "nothing", Mark H Weaver, 2018/08/28
- Re: A value for "nothing", Mark H Weaver, 2018/08/28
- Re: A value for "nothing", John Cowan, 2018/08/28
- Re: A value for "nothing", Mark H Weaver, 2018/08/28
- Re: A value for "nothing", Mark H Weaver, 2018/08/28
Re: A value for "nothing", Panicz Maciej Godek, 2018/08/26
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