Re: question regarding substitute* and #t

[Mark H Weaver <mhw@netris.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