Re: Disjoint types in SRFIs Wolfgang Corcoran-Mathe 19 Jun 2021 17:08 UTC

On 2021-06-19 12:02 +0200, Marc Nieper-Wißkirchen wrote:
> "Fxmappings (pronounced "fix-mappings") form a new type, as if created by
> define-record-type (see R7RS § 5.5). In systems supporting R6RS record-type
> semantics, fxmappings are instances of a sealed, opaque, nongenerative
> record type with uid fxmapping-7a1f4d5b-a540-462b-82b1-47283c935b85. The
> effects of using record-type inspection or inheritance for the fxmapping
> type are unspecified."
>
> The first sentence remains meaningless, the semantic implications of the
> second should also hold for R7RS schemes, and the final sentence sounds
> superfluous at best as the sentence before that talks about a sealed and
> opaque record type.

I agree that this is a little confusing.  Since the new draft hasn't
been pulled yet, I'll split out the R6RS-specific semantics as a
separate paragraph.  Re: Marc Feeley's comments, I'm also not
convinced that 'sealed' is the right choice here.

I'm not in favor of just requiring R6RS record semantics here.  The
notion of a disjoint type seems to work well enough in R5+ and R7,
and there are not, as far as I know, any other SRFIs which explicitly
use R6 record semantics instead.  So I'd like the original text to
stay.

--
Wolfgang Corcoran-Mathe  <xxxxxx@sigwinch.xyz>

"Correctness is clearly the prime quality.  If a system does
not do what it is supposed to do, then everything else about
it matters little." --Bertrand Meyer