GNU bug report logs - #38236
R7RS reader does not support datum labels

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Package: guile;

Reported by: Andy Wingo <wingo <at> pobox.com>

Date: Sat, 16 Nov 2019 20:50:02 UTC

Severity: normal

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Message #8 received at 38236 <at> debbugs.gnu.org (full text, mbox):

From: John Cowan <cowan <at> ccil.org>
To: Andy Wingo <wingo <at> pobox.com>
Cc: 38236 <at> debbugs.gnu.org
Subject: Re: bug#38236: R7RS reader does not support datum labels
Date: Sat, 16 Nov 2019 17:41:18 -0500
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I don't see where the incompatibility comes in, although more lookahead
would be required.  Per the Guile documentation, neither #n# nor #n= (where
n is a sequence of digits) is a valid array tag.

On Sat, Nov 16, 2019 at 3:50 PM Andy Wingo <wingo <at> pobox.com> wrote:

> R7RS defines a lexical feature called "datum labels"; see section 2.4 in
> the report.  An example would be:
>
>    #0=(a b c . #0#)
>
> Guile's reader doesn't support this feature and it's not clear if we
> should, in general.  Note, datum literals appear to be incompatible with
> array literals.  But we could of course use the R7RS layer as a place to
> experiment with a `read' implemented in Scheme.
>
>
>
>
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This bug report was last modified 5 years and 239 days ago.

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