[patrec]

Nix basically already does this, apart from the decentralised distributed cache (there is a centralised one and you can easily set up your own, too). All references, including to dynamically linked libraries are via unique, content addressable hash -- where "content" currently still happens to be content of the build recipe and all dependencies and sources, recursively, not the built artefact. There is work on referencing artefacts by the binary output hash though, because that obviously has better security properties when you want to have a non-centralized cache; the main problem is that a lot of software still has no reproducible build.