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Re: A value for "nothing"

From: Mark H Weaver
Subject: Re: A value for "nothing"
Date: Tue, 28 Aug 2018 13:15:35 -0400
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux)

John Cowan <address@hidden> writes:

> On Tue, Aug 28, 2018 at 11:40 AM Mark H Weaver <address@hidden> wrote:
>  That's the phrase used in R7RS-small, which fails to define it, as you
>  noted, but that shortcoming is limited to R7RS.
> The relevant sentences in R5RS and R7RS are identical: " If <test>
> yields a false value and no <alternate> is specified, then the result
> of the expression is unspecified."  Likewise, the paragraph from 1.3.2
> you quote below is identical in both standards.  So either they both
> define it or they both don't.
>  In R6RS, section 11.4.3 (Conditionals) provides this example:
> Unlike Wil Clinger, and apparently you, I don't believe that examples
> in specs are normative.

Alright, well, the formal denotational semantics makes it 100%
unambiguous, as I noted in my previous email.


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