Got to agree with davexunit here.  Language package managers aren&#x27;t going to handle your non-&lt;language&gt; dependencies.  One place where this comes up in spades is with numerical software.  Example: frequently you want to build numpy&#x2F;scipy with fast math libraries (BLAS, mkl, etc.), which might be in C, Fortran or whatever.  Python&#x27;s myriad custom package managers have no support for that level of customization so you&#x27;re back to manual installs.<p>Spack [1] attempts to solve this by allowing extensions [2,3] for languages that have their own module systems. Basically you can embed language-specific module enablement logic in the package, and you can enable&#x2F;disable packages in particular Python installs.  You can then build several versions of numpy with different dependency libraries and swap them in and out.  It&#x27;s a compromise between language and system package managers.  Right now it&#x27;s too stateful in that the modules are linked&#x2F;unlinked into a python installation.  We have plans to provide something more like virtualenv or conda environments.<p>Functional package managers are nice, as are reproducible builds, but they come up short for customizability.  I&#x27;d have to write an awful lot of packages with Nix and Guix to try out many different versions, compilers, dependencies, etc. Spack has a syntax [4] that allows these to be composed arbitrarily.  It&#x27;s not fully reproducible right now (though it could be if we went down to glibc and used a chroot jail), but the packages are much more composable than the current crop of functional package managers.<p>[1] <a href="http:&#x2F;&#x2F;github.com&#x2F;llnl&#x2F;spack&#x2F;" rel="nofollow">http:&#x2F;&#x2F;github.com&#x2F;llnl&#x2F;spack&#x2F;</a><p>[2] <a href="http:&#x2F;&#x2F;software.llnl.gov&#x2F;spack&#x2F;basic_usage.html#extensions-python-support" rel="nofollow">http:&#x2F;&#x2F;software.llnl.gov&#x2F;spack&#x2F;basic_usage.html#extensions-p...</a><p>[3] <a href="http:&#x2F;&#x2F;software.llnl.gov&#x2F;spack&#x2F;packaging_guide.html#extensions" rel="nofollow">http:&#x2F;&#x2F;software.llnl.gov&#x2F;spack&#x2F;packaging_guide.html#extensio...</a><p>[4] <a href="http:&#x2F;&#x2F;software.llnl.gov&#x2F;spack&#x2F;basic_usage.html#specs-dependencies" rel="nofollow">http:&#x2F;&#x2F;software.llnl.gov&#x2F;spack&#x2F;basic_usage.html#specs-depend...</a>