Re: [PATCH 6/6] gnu: Improve error reporting of the use-.*modules macros.

[Ludovic Courtès]

Heya,

Chris Marusich <address@hidden> skribis:

> Ludovic Courtès <address@hidden> 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’s necessary because ‘use-modules’ (and ‘try-use-modules’ here)
doesn’t allow you to specify the “phase” (run-time or expansion-time) at
which you’re “using” the module.  Thus, it assumes you’re using it both
at expansion-time and at run-time.

The (gnu packages …) modules happen to export a few macros, so it
doesn’t work if you import them at run-time only.

Ludo’.