From mboxrd@z Thu Jan  1 00:00:00 1970
From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: gexps and =?utf-8?Q?=E2=80=98with-imported-modules=E2=80=99?=
Date: Mon, 04 Jul 2016 15:39:28 +0200
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In-Reply-To: <87wpl1j16z.fsf@gmail.com> (Alex Kost's message of "Mon, 04 Jul
	2016 10:45:56 +0300")
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To: Alex Kost <alezost@gmail.com>
Cc: guix-devel <guix-devel@gnu.org>

Alex Kost <alezost@gmail.com> skribis:

> Ludovic Court=C3=A8s (2016-07-04 01:20 +0300) wrote:
>
>> Hello!
>>
>> The =E2=80=98wip-gexp-imported-modules=E2=80=99 branch changes gexps so =
that each gexp
>> embeds information about which modules need to be imported into its
>> execution environment.
>>
>> Before you would do:
>>
>>   (gexp->derivation "foo"
>>                     #~(begin
>>                         (use-modules (guix build utils))
>>                         =E2=80=A6)
>>                     #:modules '((guix build utils)))
>>
>> to specify that (guix build utils) must be imported in the build
>> environment of =E2=80=9Cfoo=E2=80=9D.  After, it becomes:
>>
>>   (gexp->derivation "foo"
>>                     (with-imported-modules '((guix build utils))
>>                       #~(begin
>>                           (use-modules (guix build utils))
>>                           =E2=80=A6)))
>>
>> The gain (not visible here) is that when you nest gexps, the outermost
>> gexp now contains all the info about modules that need to be imported.
>> That way, no side channel is needed to carry the imported module info
>> (by =E2=80=9Cside channel=E2=80=9D, I mean things like the =E2=80=98impo=
rted-modules=E2=80=99 field
>> currently found in <shepherd-service> and several other places.)  Thus,
>> it should be easier to compose gexps.
>
> Great!  I like 'with-...' things.  And wow, you did a huge work again!

Thank you.  I think it=E2=80=99ll be beneficial.  It makes more sense to pr=
ovide
imported-module info at the gexp creation site rather than at the use
site.

>> I plan to merge it within a day or two.
>>
>> Comments welcome!
>
> I see you added the indentation rule for 'with-imported-modules' in
> "emacs/guix-devel.el".  I think it would also be good to add it to
> 'guix-devel-keywords' (as you did in commit cd6f6c22fb) to make it
> highlighted as the other keywords.

Will do!

Ludo=E2=80=99.