Without Flakes

new-scope — named aspect namespaces

new-scope creates an isolated aspect namespace within any lib.evalModules evaluation:

let
  result = lib.evalModules {
    modules = [
      (new-scope "my")
      {
        my.aspects = { aspects, ... }: {
          laptop = {
            nixos = { pkgs, ... }: { environment.systemPackages = [ pkgs.vim ]; };
            includes = [ aspects.base ];
          };
          base.nixos = { lib, ... }: { networking.hostName = "laptop"; };
        };
      }
    ];
  };
in
  lib.nixosSystem { modules = [ result.config.my.modules.nixos.laptop ]; }

new-scope "my" creates:

• my.aspects — input: aspect definitions (type: aspectsType)
• my.modules — output: transposed + resolved modules (read-only)

Note

Test: without_flakes.nix

Multiple scopes

Independent scopes can coexist and merge. Each creates its own <name>.aspects / <name>.modules pair:

modules = [
  (new-scope "foo")
  (new-scope "bar")
  { foo.aspects.a.nixos.x = [ "from-foo" ]; }
  { bar.aspects.a.nixos.x = [ "from-bar" ]; }
  ({ config, ... }: { bar = config.foo; })  # merge foo into bar
];

After merging, bar.modules.nixos.a contains both "from-foo" and "from-bar".

Note

Test: aspect_assignment.nix

new — low-level factory

new is the callback-based primitive underneath new-scope:

new (option: transposed: {
  options.myLib.aspects = option;
  config.myLib.modules = transposed;
}) config.myLib.aspects

new-scope is sugar for the common ${name}.aspects / ${name}.modules pattern. Use new directly when you need custom option paths or additional logic in the callback.

Useful for libraries that want isolated aspect scopes or flake-parts independence (see Den’s scope).