From mboxrd@z Thu Jan  1 00:00:00 1970
From: Mark H Weaver <mhw@netris.org>
Subject: Re: question regarding substitute* and #t
Date: Wed, 24 Jan 2018 08:28:06 -0500
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	<874lnbzck5.fsf_-_@netris.org> <87372v8ndd.fsf_-_@igalia.com>
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In-Reply-To: <87372v8ndd.fsf_-_@igalia.com> (Andy Wingo's message of "Wed, 24
	Jan 2018 13:14:38 +0100")
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To: Andy Wingo <wingo@igalia.com>
Cc: guix-devel@gnu.org

Hi Andy,

Andy Wingo <wingo@igalia.com> writes:

> On Wed 24 Jan 2018 13:06, Mark H Weaver <mhw@netris.org> writes:
>
>> +             ;; Install to the right directory
>> +             (substitute* '("Makefile"
>> +                            "Qsci/Makefile")
>> +               (("\\$\\(INSTALL_ROOT\\)/gnu/store/[^/]+")
>> +                (assoc-ref outputs "out")))
>> +             #t)))))
>
> I guess once we switch over all instances of "system" and "system*" to
> use invoke, does that mean we will also be able to remove these
> vestigial "#t" returns?

After we switch to using 'invoke' everywhere, or more precisely, after
we arrange to never return #false from any phase or snippet, then there
should be one more step before removing the vestigial #true returns: we
should change the code that calls phases or snippets to ignore the
value(s) returned by those procedures.  When that is done, then the #t's
will truly be vestigial.  Does that make sense?

      Mark