From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Bavier <ericbavier@openmailbox.org>
Subject: Re: Reverse dependencies
Date: Thu, 11 Aug 2016 14:13:04 -0500
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To: Vincent Legoll <vincent.legoll@gmail.com>
Cc: help-guix <help-guix@gnu.org>

On 2016-08-11 09:43, Vincent Legoll wrote:
> Hello,
> 
>>> I'm trying to understand which package(s) depends on some other 
>>> package,
>>> kind of the reverse of what guix graph does (I think).
>> 
>> I think that `guix refresh --list-dependent foo` is what you are 
>> asking
>> for, or at least it's close. We use it to learn what will need to be
>> rebuilt when upgrading foo.
> 
> Not really what I want to know:
> 
> # guix refresh --list-dependent inkscape
> Building the following 5 packages would ensure 10 dependent packages
> are rebuilt: frescobaldi-2.19.0 solfege-3.22.2 simple-scan-3.19.91
> termite-11 hydra-20150407.4c0e3e4
> 
> None of those are installed, but inkscape is pulled in by something
> which I want to know
> 
> Is there no other way to get that information ?

Something like (mildly tested):

(use-modules (guix packages)
              (gnu packages)
              (gnu packages inkscape)
              (srfi srfi-1)
              (srfi srfi-26))

(fold-packages
   (lambda (package _)
     (when (any (cut eq? <> inkscape)
                (map second (package-direct-inputs package)))
       (format #t "~a depends on inkscape~%"
               (package-full-name package))))
   #t)

which, when run, results in:
"dblatex-0.3.5 depends on inkscape"

-- 
`~Eric