lib.types: chore use consistent payload form

[hsjobeki]

Use attributeSet for functor.payload consistently. This reduces complexity and allows to move generic logic for payload handling out of the individual types.

types.separatedString
types.enum

Are the only ones that don't use attribute sets for their payload.

I'd like to introduce this convention. Maybe we should add a CI check.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 25.05 Release Notes (or backporting 24.11 and 25.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[infinisil]

Looked at it together with @hsjobeki in a call, LGTM with the release notes!

[PerchunPak]

mergeEnums is a use-case that this PR broke:

https://github.com/catppuccin/nix/blob/a817009ebfd2cca7f70a77884e5098d0a8c83f8e/modules/lib/default.nix#L133-L137
https://github.com/catppuccin/nix/blob/a817009ebfd2cca7f70a77884e5098d0a8c83f8e/modules/home-manager/cursor.nix#L12

Fix is:

-mergeEnums = a: b: lib.types.enum (a.functor.binOp a.functor.payload b.functor.payload);
+mergeEnums = a: b: lib.types.enum (a.functor.binOp a.functor.payload b.functor.payload).values;

[infinisil]

@PerchunPak Thanks for reaching out, we were thinking of that exact piece of code when discussing this PR! Since .payload is internal (for now), I don't recommend relying on it. Instead you can use this to merge types:

mergeEnums = a: b: a.typeMerge b.functor;

While .typeMerge and .functor are also somewhat internal, they can be expected to stay more stable.

[roberth]

Any reason not to add that to lib?

mergeTypes = a: b: a.typeMerge b.functor;

[infinisil]

Oh yeah, good idea

[nixos-discourse]

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/breaking-changes-announcement-for-unstable/17574/72

[nixos-discourse]

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/breaking-changes-announcement-for-unstable/17574/73

[hsjobeki]

Any reason not to add that to lib?

mergeTypes = a: b: a.typeMerge b.functor;

Made a pr for that #364620

[nixos-discourse]

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/use-cases-of-option-type-internals/57317/1