Like Nix but GNU.
Ranked in these QuestionsQuestion Ranking
Pro No side effects when building packages
Guix is a purely functional package management system. This means that the act of building a package does not have side effects, such as destructively updating or deleting files that may be used by other packages.
Con Cannot handle filetypes that have different semantics across different versions
While the functional approach that Guix takes is great for sandboxing binary artifacts of packages, it seriously lacks any power in handling configuration files or user data. It's difficult to upgrade and downgrade files where semantics and syntax can change between versions. Especially in Debian/Ubuntu it can cause severe problems where the upgrade process blocks and the user needs to resolve the 3-way merge.