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From: bokr@bokr.com
To: "Ludovic Courtès" <ludo@gnu.org>
Cc: 56799@debbugs.gnu.org, attila@lendvai.name,
	Maxim Cournoyer <maxim.cournoyer@gmail.com>
Subject: bug#56799: (gnu services configuration) usage of *unspecified* is problematic
Date: Tue, 2 Aug 2022 10:45:30 +0200	[thread overview]
Message-ID: <20220802084530.GA5603@LionPure> (raw)
In-Reply-To: <87v8rbumnx.fsf@gnu.org>

Hi,

On +2022-08-02 09:31:14 +0200, Ludovic Courtès wrote:
> Hi,
> 
> Maxim Cournoyer <maxim.cournoyer@gmail.com> skribis:
> 
> > Ludovic Courtès <ludo@gnu.org> writes:
> >
> >> Hi!
> >>
> >> Maxim Cournoyer <maxim.cournoyer@gmail.com> skribis:
> >>
> >>> Since commit 8cb1a49a3998c39f315a4199b7d4a121a6d66449, the
> >>> define-configuration machinery in (gnu services configuration) uses
> >>> *unspecified* instead of 'disabled for an unspecified field value.
> >>
> >> As Attila wrote, the rationale as discussed in
> >> <https://issues.guix.gnu.org/54674> was to specifically use a “special”
> >> value without a read syntax in lieu of a symbol like 'disabled.
> >>
> >>> While this is indeed an improvement in readability, it introduces an
> >>> extra complication: because this new value is not self-quoting, it
> >>> cannot be used as is in G-Exps, and values using it must be carefully
> >>> expanded outside the gexp context, which is error prone.
> >>
> >> Could you give a simple example of how this can happen?
> >>
> >> In my experience, one would use ‘define-maybe’ and appropriate field
> >> serializers such that *unspecified* never goes through.  Previously
> >> you’d check for (eq? x 'disabled) and now you just check for
> >> (unspecified? x).
> >
> > Yes, I understand that.  What changed is that previously you could have
> > the configuration serialized and used on the service side, which is what
> > using *unspecified* made impossible.
> 
> Do you have an example?  Even on the service side, I imagine one could
> check for ‘unspecified?’ just like one would check for 'disabled, no?
> 
> > Granted, few services outside of Jami probably made use of this, but it
> > was nevertheless a useful property.
> 
> I don’t know of any.
> 
> Having spent time reviewing the original change that Attila proposed and
> then chiming in on this issue, I would have hoped for a longer
> discussion before enacting the change in
> a2b89a3319dc1d621c546855f578acae5baaf6da.
> 
> In addition to these issues around the process, I think we should strive
> for more stability.  One of the reasons it took time to review
> <https://issues.guix.gnu.org/54674> is that interface changes are a
> commitment.  Now commit a2b89a3319dc1d621c546855f578acae5baaf6da
> introduces a second interface change for reasons that are unclear to me
> (if the conclusion had been to revert, I’d have favored an actual revert
> rather than introducing 'unset).
> 
> How should we move forward?
>

My 2¢ :

Maybe separate commmit churn more formally into a
release candidate series like Linus does for linux kernel,
and have a long term stable guix only get what is agreed
with solid consensus?

AND, importantly: where issues involve subtleties
of abstract entities vs their concrete representations,
make sure this is clearly documented in the commit rationale,
e.g., maybe using denottional semantics[1] like r5rs ?

[1]:  <https://en.wikipedia.org/wiki/Denotational_semantics>

:)

> Thanks,
> Ludo’.
>
--
Regards,
Bengt Richter
OT PS: Has Boot-to-guile been updated by anyone?
Kudos for the original! :) A RISCV qemu image? :)




  reply	other threads:[~2022-08-02  9:22 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-27 16:23 bug#56799: (gnu services configuration) usage of *unspecified* is problematic Maxim Cournoyer
2022-07-27 16:43 ` Tobias Geerinckx-Rice via Bug reports for GNU Guix
2022-07-27 18:27   ` Attila Lendvai
2022-07-28 15:15     ` Maxim Cournoyer
2022-07-27 18:31   ` Maxim Cournoyer
2022-07-27 18:45     ` Tobias Geerinckx-Rice via Bug reports for GNU Guix
2022-07-27 19:09       ` Maxim Cournoyer
2022-07-27 19:45         ` bug#56799: [PATCH] services: configuration: Step back from *unspecified* Maxim Cournoyer
2022-07-27 19:46         ` bug#56799: (gnu services configuration) usage of *unspecified* is problematic Maxim Cournoyer
2022-07-27 20:20           ` bug#56799: [PATCH v2] gexp: Handle *unspecified* as a gexp input Maxim Cournoyer
2022-07-27 21:43             ` Maxime Devos
2022-07-28 14:58               ` Maxim Cournoyer
2022-07-28  4:41           ` bug#56799: [PATCH v3] " Maxim Cournoyer
2022-08-01  5:08             ` bug#56799: (gnu services configuration) usage of *unspecified* is problematic Maxim Cournoyer
2022-08-01 10:00               ` Maxime Devos
2022-08-01 12:46                 ` Maxim Cournoyer
2022-08-01 13:44             ` Ludovic Courtès
2022-08-01 16:55       ` Maxim Cournoyer
2022-07-28  4:55     ` bokr
2022-07-28 10:26       ` Maxime Devos
2022-07-28 15:09         ` Maxim Cournoyer
2022-08-01 13:49 ` Ludovic Courtès
2022-08-01 15:55   ` Maxim Cournoyer
2022-08-02  7:31     ` Ludovic Courtès
2022-08-02  8:45       ` bokr [this message]
2022-08-02 15:06       ` Maxim Cournoyer
2022-08-04 12:19         ` Ludovic Courtès
2022-08-07 22:44           ` Ludovic Courtès
2022-08-08 22:27           ` Attila Lendvai
2022-08-08 23:35             ` Attila Lendvai
2022-08-10  2:17               ` Maxim Cournoyer
2022-08-10  3:26             ` Maxim Cournoyer
2022-08-11 10:15               ` Attila Lendvai
2022-08-13  6:31                 ` Maxim Cournoyer
2022-08-13 16:47                   ` Attila Lendvai
2022-08-14  2:57                     ` Maxim Cournoyer
2022-08-16 14:00                       ` Attila Lendvai
2022-08-17 13:16                         ` Maxim Cournoyer
2022-08-17 16:00                           ` paren--- via Bug reports for GNU Guix
2022-08-10  0:43           ` Maxim Cournoyer
2022-08-24 12:40 ` bug#56799: [PATCH 1/5] services: configuration: Add a 'maybe-value-set?' procedure Attila Lendvai
2022-08-24 12:40   ` bug#56799: [PATCH 2/5] services: configuration: Add %unset-value exported variable Attila Lendvai
2022-08-24 12:40   ` bug#56799: [PATCH 3/5] services: configuration: Add maybe-value exported procedure Attila Lendvai
2022-08-24 12:40   ` bug#56799: [PATCH 4/5] services: Use the new maybe/unset API Attila Lendvai
2022-08-25  4:18     ` bug#56799: (gnu services configuration) usage of *unspecified* is problematic Maxim Cournoyer
2022-08-24 12:40   ` bug#56799: [PATCH 5/5] services: configuration: Change the value of the unset marker Attila Lendvai
2022-08-25  4:14     ` bug#56799: (gnu services configuration) usage of *unspecified* is problematic Maxim Cournoyer

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