nomenclature surrounding derivations

[tejing1]

There's a lot of ambiguity and confusion surrounding the terms "package" and "derivation" currently. It would be good to provide a consistent set of terminology in this book.

The current situation I see in the community:

• "package" is vaguely used to refer to "derivations" (with all the multiplicity of meaning inherent there) which fit the intuitive notion of a package in more typical package managers.
• "derivation" is used to refer to many distinct things in my experience:
  • nix files containing nix expressions invoking the derivation keyword or other functions which wrap it. These are further subdivided by the external interface the code in the file conforms to:
  • callPackage /path/to/file.nix { ... }
  • import /path/to/file.nix { ... }
  • import /path/to/file.nix
  • nix expressions invoking the derivation keyword or other functions which wrap it.
  • nix language values produced by the derivation keyword or other functions which wrap it.
  • *.drv files in the nix store generated from those expressions
  • the build process described by the *.drv file
  • the store object produced by the build process
  • the store path of that store object

We need to set some precedents about how we refer to these concepts. Some overloading is probably appropriate, but not this much.

[hugosenari]

• Packaging/Package:

292 mention Teaching Tech Together that says: Never hesitate to sacrifice truth for clarity.

And Teaching Tech Together mention Hattie Effect Sizes, one of it points are -0.29 for non standard dialect use (that if I get it right is teacher speaking a language uncommon to students) and we usually speak 'academic dialects' where most of our students are more practical (street smart) than academical (book smart)

I wish, I never had to say 'derivation' to anyone.

• "Derivation":
  • "nix file with derivations output": I have no idea what we could do here, but in fact is a 'different issue', unlike most programming, nix has a single output (there is a term for that?), for this reason we usually refer to the file as what we expect from it, I'm having this problem trying to explain Flake, a flake.nix file expects an attrset, but adding another node make it verbose...
  • "nix expressions invoking the derivation", I think is the same, at least for console/repl
  • "nix language values", are the derivative?
  • "*.drv files", should be .drv files, like .nix files aren't nix', I would change to .lock
  • "the build process" should be the build process, but I think derivation make sense here.
  • "the store object" is the derivative?
  • the store path of that store object (that resemble to the first problem now would be derivative)