Based on my experience, this also isn&#x27;t true.  I added support for Ruby gems in the GNU Guix package manager.  The way it was done was by creating a Ruby-specific build system that Ruby-based software packages elect to use.  We have a generic model that allows for many types of specific build systems to exist that deal with the domain-specific concerns.  This generic models works <i>better</i> than a Ruby-specific model because, unlike RubyGems, Guix can capture the <i>entire</i> dependency graph.<p>Take the Pg gem, for example.  In order to build and use it, you need the libpq shared library.  RubyGems can&#x27;t encode this dependency, but Guix can.  The recipe for ruby-pg is only 25 lines long: <a href="http:&#x2F;&#x2F;git.savannah.gnu.org&#x2F;cgit&#x2F;guix.git&#x2F;tree&#x2F;gnu&#x2F;packages&#x2F;ruby.scm#n2669" rel="nofollow">http:&#x2F;&#x2F;git.savannah.gnu.org&#x2F;cgit&#x2F;guix.git&#x2F;tree&#x2F;gnu&#x2F;packages&#x2F;...</a><p>There was a talk given at FOSDEM about foreign packages in Guix with a focus on Ruby which is worth watching or skimming the slides: <a href="https:&#x2F;&#x2F;fosdem.org&#x2F;2016&#x2F;schedule&#x2F;event&#x2F;guixmodules&#x2F;" rel="nofollow">https:&#x2F;&#x2F;fosdem.org&#x2F;2016&#x2F;schedule&#x2F;event&#x2F;guixmodules&#x2F;</a>