Re: Proposal: Make Guile 4.0 support R6RS/R7RS by default

"Dr. Arne Babenhauserheide" <[email protected]> Mon, 06 Oct 2025 12:09:05 +0200

Newsgroups	gmane.lisp.guile.devel
Message-ID	<[email protected]>

Daphne Preston-Kendal <[email protected]> writes:

> With talk of Guile 4.0 in the air, I’d like to propose that this
> version should be taken as an opportunity to enable --r6rs and --r7rs
> modes by default.

In general this sounds good to me, except for the backwards
compatibility breakage. Is that breakage actually required?

> Worse, due to the standard layout for many R7RS libraries (with a .sld
> declaration which includes a .scm source file of the same base name),
> Guile started in its default mode will try to load the wrong file when
> importing such libraries, which doesn’t actually include any library
> declaration – giving the illusion that Guile doesn’t support an R7RS
> library, when in fact it would probably work fine with the --r7rs
> flag.
…
> surprising results in the case of libraries which have a .scm version
> targeting Guile besides a .sld version targetting standard R7RS. I
> have created such a library myself (the SRFI 250 sample

How many libraries of each kind are there?

Would a smaller change of using the .scm first and .sld second by
default and changing --r7rs to only change the order be sufficient?

Then no currently working library would break on update and some r7rs
libraries would be added as compatible, but not all. Specifying --r7rs
would then only switch the preference around: prefer supporting r7rs
over supporting guile specifics.

> The second change will be harder to make. I suggest that if possible,
> the next minor release of Guile should begin warning about the
> deprecation of \xNN string escapes with no semicolon when the reader
> encounters one; then Guile 4.0 can turn them off by default.

What’s the advantage of removing support for those escapes?

Best wishes,
Arne
-- 
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heißt politisch sein,
ohne es zu merken.
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