From: "Linus Björnstam" <linus.bjornstam@veryfast.biz>
To: guile-devel@gnu.org
Subject: Re: [Patch] definitions in when, unless, do as well as in cond- and case-clauses
Date: Thu, 03 Feb 2022 11:48:22 +0100 [thread overview]
Message-ID: <7f58438c-f2fb-49b6-b7b0-22054fde6277@www.fastmail.com> (raw)
In-Reply-To: <e3147bb6-48ba-4abf-90af-557de360cbdd@www.fastmail.com>
Hi guys,
It looks like a 3.0.8 might be happening. I am curious to know whether this (perhaps minus the do form) is considered something that the maintainers of guile could find interesting.
If subset compatibility of r6|7rs is desired, I could provide a patch for those files as well so that they enforce the distinction between definition and expression context.
I myself find this a worthwhile patch since it has no drawbacks. a (let () ...) without definitions does not start a new lexical context and runs as fast as a begin, so there should be no performance regressions.
It also removes the last bodies in guile forms that have a definition context, which may be confusing for beginners.
I would say that the compatibility question with the enforcing cond of rnrs is the only thing that needs proper addressing.
Best
Linus Björnstam
On Wed, 16 Jun 2021, at 21:11, Linus Björnstam wrote:
> Hi there!
>
> This patch updates some derived conditional forms (and do and and-let*)
> to support definitions in expression context. Meaning it makes this
> valid code:
>
> (cond
> ((pred? arg)
> (define a (something arg))
> (when (error-case a)
> (error "a is broken"))
> (define b (something2 a))
> (when (= 3 *log-level*)
> (display "logging something1 and 2 as successful"))
> (define c (something3 b a))
> (when (odd? c)
> (error "something went wrong in something3"))
> c)
> (else
> ;;chosen by fair dice roll. Guaranteed to be random
> 4)))
>
> While awful, is sometimes what the world makes us do.
>
> The change means cond, case, when and unless behaves like it does in
> racket. Do was below case, so I changed that as well, and will actually
> become yet another way guile is superior to racket.
>
> I did also change the documentation, but I learned english by watching
> Beverly Hills cop, so that might need some fine touches by a capable
> english speaker.
>
>
> Best regards
> Linus Björnstam
> Attachments:
> * 0001-Allow-definitions-in-derived-conditional-forms.patch
next prev parent reply other threads:[~2022-02-03 10:48 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-16 19:11 [Patch] definitions in when, unless, do as well as in cond- and case-clauses Linus Björnstam
2021-06-17 9:06 ` Maxime Devos
2021-06-17 12:57 ` Linus Björnstam
2021-06-17 13:54 ` Maxime Devos
2022-02-03 10:48 ` Linus Björnstam [this message]
[not found] ` <CAGua6m1Cqe=aLOD7-jfzoqxP1aOxvWn3=UgcKyk+Dx7_51Bq3w@mail.gmail.com>
2022-02-04 20:11 ` Fwd: " Stefan Israelsson Tampe
2022-02-04 20:58 ` Maxime Devos
[not found] ` <CAGua6m11r27x=rq4S4fF09vHY+S-Az7GOZfmoT41hEBDSkLJQg@mail.gmail.com>
2022-02-04 21:40 ` Fwd: " Stefan Israelsson Tampe
2022-02-04 23:39 ` Maxime Devos
2022-02-05 1:14 ` Stefan Israelsson Tampe
2022-02-05 10:55 ` Maxime Devos
2022-02-05 17:31 ` Stefan Israelsson Tampe
2022-02-05 17:36 ` Maxime Devos
2022-02-06 6:44 ` Linus Björnstam
2022-02-06 9:27 ` tomas
2022-02-06 9:40 ` Maxime Devos
2022-02-06 9:45 ` Linus Björnstam
2022-02-06 10:48 ` tomas
2022-02-06 20:13 ` Stefan Israelsson Tampe
2022-02-06 20:28 ` Maxime Devos
2022-02-06 20:31 ` tomas
[not found] ` <CAGua6m3BHMXOhT3PHZcxdqHqHomTFESO31j5CcSNK3pbA7K-Kg@mail.gmail.com>
2022-02-06 21:26 ` Maxime Devos
2022-02-06 21:27 ` Maxime Devos
2022-02-07 5:56 ` Linus Björnstam
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