The nix repl can be a very valuable tool in answering these questions. That said, I strive to structure my nix source so that portions of it can easily be past

The nix repl can be a very valuable tool in answering these questions. That said, I strive to structure my nix source so that portions of it can easily be pasted into a repl. ReadTree goes a long way in that regard: https://github.com/tvlfyi/kit/tree/canon/readTree https://github.com/tvlfyi/kit/tree/canon/readTree More to your point, though: I think a lot is possible. Although nix is very dynamic, it is also, for all intents and purposes, side effect free. I've had this idea that a sufficiently advanced IDE should be able to evaluate your nix code and tell you exactly what the possible values (not just types, but value!) are for any particular variable.