Yeah. Somewhat notably, GNU Ada/gnat has been broken in Nix forever, and generally the difficulties of making things work correctly under Nix is great enough that some stuff is pretty hard to keep up to date or available at all. Of course it works well for almost everything, but there are limitations; it definitely is a complex thing.

edit: It looks like my information might be out of date as it appears gnat is back in Nixpkgs. That's great news, although I think the point regarding complexity still stands, since I believe it was broken for quite a while at some point, and broke a few times since too.

Ok, we've Nix'd the title above. Thanks!