WIP: more type-safe policy application

deployment/data-model-test.nix

@@ -45,10 +45,10 @@ in
                       extra-config = mkOption {
                         description = "Any options from NixOS";
                       };
-                      apply = mkOption {
-                        type = with types; functionTo raw;
-                        default = policy: requests: lib.mkMerge (requests ++ [ policy.extra-config ]);
                     };
+                    config = {
+                      resource-type = types.raw; # TODO: what's the type of a NixOS configuration?
+                      apply = policy: requests: lib.mkMerge (requests ++ [ policy.extra-config ]);
                     };
                   };
               };
@@ -85,9 +85,10 @@ in
                         type = types.bool;
                         default = false;
                       };
-                      apply = mkOption {
-                        type = with types; functionTo raw; # TODO: splice out the user type from NixOS
-                        default =
+                    };
+                    config = {
+                      resource-type = types.raw; # TODO: splice out the user type from NixOS
+                      apply =
                         policy: requests:
                         let
                           # Filter out requests that need wheel if policy doesn't allow it
@@ -103,7 +104,6 @@ in
                     };
                   };
               };
-              };
               applications.hello =
                 { ... }:
                 {
@@ -120,7 +120,9 @@ in
                   resources =
                     cfg:
                     lib.optionalAttrs cfg.enable {
-                      dummy.login-shell.packages.hello = pkgs.hello;
+                      hello.login-shell.packages = {
+                        inherit (pkgs) hello;
+                      };
                     };
                 };
               environments.single-nixos-vm = environment: {

deployment/data-model.nix

@@ -72,11 +72,26 @@ in
                   type = submoduleWith {
                     class = "fediversity-resource-policy";
                     modules = [
-                      {
-                        options.apply = mkOption {
-                          description = "Apply the policy to a request";
+                      (policy: {
+                        _class = "fediversity-resource-policy";
+                        options = {
+                          # TODO(@fricklerhandwerk): not sure it can be made
+                          # sensible syntactically, but essentially we want to
+                          # ensure that `apply` is defined, but since its output
+                          # depends on the specific policy we also need to
+                          # determine that somehow.
+                          # hopefully this also helps with correct composition down the line.
+                          resource-type = mkOption {
+                            description = "The type of resource this policy configures";
+                            type = types.optionType;
                           };
-                      }
+                          # TODO(@fricklerhandwerk): do we need a function type here as well, or is it in the way?
+                          apply = mkOption {
+                            description = "Apply the policy to a request";
+                            type = functionTo policy.config.resource-type;
+                          };
+                        };
+                      })
                     ];
                   };
                 };