From mboxrd@z Thu Jan  1 00:00:00 1970
From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: [PATCH 6/6] gnu: Improve error reporting of the use-.*modules
	macros.
Date: Sat, 11 Nov 2017 14:56:37 +0100
Message-ID: <87h8u0hqay.fsf@gnu.org>
References: <87zi7xwvso.fsf_-_@gnu.org> <20171108130921.25202-1-ludo@gnu.org>
	<20171108130921.25202-7-ludo@gnu.org> <87d14po9mv.fsf@gmail.com>
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In-Reply-To: <87d14po9mv.fsf@gmail.com> (Chris Marusich's message of "Fri, 10
	Nov 2017 18:02:32 -0800")
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To: Chris Marusich <cmmarusich@gmail.com>
Cc: guix-devel@gnu.org

Heya,

Chris Marusich <cmmarusich@gmail.com> skribis:

> Ludovic Court=C3=A8s <ludo@gnu.org> writes:
>
>> +(define-syntax-rule (try-use-modules hint modules ...)
>> +  (eval-when (expand load eval)
>> +    (%try-use-modules '(modules ...)
>> +                      (source-properties->location
>> +                       (current-source-location))
>> +                      hint)))
>> +
>
> Why is it necessary to use eval-when here?  The Guile manual makes it
> sound like eval-when is intended to be used with syntax-case macros, not
> syntax-rules macros.

It=E2=80=99s necessary because =E2=80=98use-modules=E2=80=99 (and =E2=80=98=
try-use-modules=E2=80=99 here)
doesn=E2=80=99t allow you to specify the =E2=80=9Cphase=E2=80=9D (run-time =
or expansion-time) at
which you=E2=80=99re =E2=80=9Cusing=E2=80=9D the module.  Thus, it assumes =
you=E2=80=99re using it both
at expansion-time and at run-time.

The (gnu packages =E2=80=A6) modules happen to export a few macros, so it
doesn=E2=80=99t work if you import them at run-time only.

Ludo=E2=80=99.