On Tue, Aug 28, 2018 at 11:40 AM Mark H Weaver <[email protected]> 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. But setting that aside for the moment: > I take the use of the singular form of "value" here to imply that it > returns only one value. > In R6RS 11.13, vector-set! is said to return unspecified values (note plural), but in the examples appears "⇒ unspecified", showing that this notation can be used where multiple unspecified values (or zero values) are allowed. In practice, I know of no Scheme implementation that returns other than one value in any of these "unspecified values" situations, which IMO is a Good Thing. -- John Cowan http://vrici.lojban.org/~cowan [email protected] With techies, I've generally found If your arguments lose the first round Make it rhyme, make it scan / Then you generally can Make the same stupid point seem profound! --Jonathan Robie
