This post is targeted at users of nix who write / maintain package derivations for software they contribute to. I’ve spent a lot of time doing (and thinking about) this, although it’s probably quite a niche audience ;)

tl;dr: you should check out nix-pin and nix-update-source if you want to have a happy life developing and updating nix expressions for projects you work on.

I believe nix is a technically excellent mechanism for software distribution and packaging.

But it’s also flexible enough that I want to use it for many different use cases, especially during development. Unfortunately, there are a few rough edges which make a good development setup difficult, especially when you’re trying to build expressions which serve multiple purposes. Each of these purpose has quite a few constraints: