repro-meow.nix

# try it yourself with:
#   nix eval --file eval.nix config.users.users.alice --show-trace

import <nixpkgs/nixos> {
  configuration =
    {
      lib,
      pkgs,
      config,
      options,
      ...
    }:
    {
      imports = [
        {
          options.meow = {
            users = lib.mkOption {
              type = lib.types.listOf lib.types.str;
              default = [ ];
            };

            defaultUserSettings = lib.mkOption {
              inherit (options.users.users) type;
              default = { };
            };
          };
        }

        {
          config = {
            meow = {
              users = [
                "alice"
                "bob"
              ];

              defaultUserSettings = {
                shell = pkgs.fish;
              };
            };

            users.users = lib.genAttrs config.meow.users (
              name: config.meow.defaultUserSettings // { inherit name; }
            );
          };
        }
      ];
    };
}