We are going to use Guix as a package manager on a bioinformatics cluster. Managing various different scientific applications at different versions with very different dependencies for different user groups is something that is incredibly painful with traditional packaging systems. Guix greatly simplifies this whole process and writing package definitions in Scheme is so much nicer than, say, writing RPM spec files.
this brings to mind the justification behind the SciPy distribution. I wonder if nix or something based on it has the potential to be used as a more generalized replacement for thinks like virtualenv? Just roll up a new user for your project with all the dependencies defined, instead of the kinda-sorta isolation of a venv and without the overhead of a vm?