Making working per-project definitions in NixOS is what ultimately got me to drop NixOS :(

The specific reason is Ruby + RoR leading to nokogiri... which is something people have been dealing with for several years and there's no solution, and I lost the one file where I managed to get it working good enough to launch rubymine in a way that sees everything necessary.

Similar issues crop in other places, due to how Nix dependencies are handled like unflattened node_modules at times :/