readability

`mapAttrs'` takes two args rather than a set, whereas if only the val
changes `mapAttrs (_: v: ...)` should do

deployment/data-model-test.nix

@@ -40,7 +40,7 @@ in
                     _class = "fediversity-resource-policy";
 
                     options = {
-                      extra-config = mkOptions {
+                      extra-config = mkOption {
                         description = "Any options from NixOS";
                       };
                       apply = mkOption {
@@ -82,23 +82,21 @@ in
                         type = types.bool;
                         default = false;
                       };
-                      apply = mkOption {
-                        type = with types; functionTo raw; # TODO: splice out the user type from NixOS
-                        default =
-                          requests:
-                          let
-                            # Filter out requests that need wheel if policy doesn't allow it
-                            validRequests = lib.filterAttrs (name: req: !req.wheel || config.wheel) requests;
-                          in
-                          lib.optionalAttrs (validRequests != { }) {
-                            ${config.username} = {
-                              isNormalUser = true;
-                              packages = with lib; concatMapAttrs (name: request: attrValues request.packages) validRequests;
-                              extraGroups = lib.optional config.wheel "wheel";
-                            };
-                          };
-                      };
                     };
+                    config.resource-type = types.any; # TODO: splice out the user type from NixOS
+                    config.apply =
+                      requests:
+                      let
+                        # Filter out requests that need wheel if policy doesn't allow it
+                        validRequests = lib.filterAttrs (_name: req: !req.wheel || config.wheel) requests;
+                      in
+                      lib.optionalAttrs (validRequests != { }) {
+                        ${config.username} = {
+                          isNormalUser = true;
+                          packages = with lib; concatMapAttrs (_name: request: attrValues request.packages) validRequests;
+                          extraGroups = lib.optional config.wheel "wheel";
+                        };
+                      };
                   };
               };
               applications.hello =
@@ -113,7 +111,9 @@ in
                   implementation =
                     cfg:
                     lib.optionalAttrs cfg.enable {
-                      dummy.login-shell.packages.hello = pkgs.hello;
+                      hello.login-shell.packages = {
+                        inherit (pkgs) hello;
+                      };
                     };
                 };
               environments.single-nixos-vm =
@@ -133,10 +133,10 @@ in
                           inputs.nixops4-nixos.modules.nixops4Resource.nixos
                         ];
                         nixos.module =
-                          { pkgs, ... }:
+                          { ... }:
                           {
                             users.users = config.resources.shell.login-shell.apply (
-                              lib.filterAttrs (name: value: value ? login-shell) requests
+                              lib.filterAttrs (_name: value: value ? login-shell) requests
                             );
                           };
                       };
@@ -164,8 +164,7 @@ in
       {
         inherit (fediversity) example-deployment;
       };
-    expected =
-      {
-      };
+    expected = {
+    };
   };
 }

deployment/data-model.nix

@@ -21,11 +21,7 @@ let
     options.resources = mkOption {
       # TODO: maybe transpose, and group the resources by type instead
       type = attrsOf (
-        attrTag (
-          lib.mapAttrs' (name: resource: {
-            ${name} = mkOption { type = resource.request; };
-          }) config.resources
-        )
+        attrTag (lib.mapAttrs (_name: resource: mkOption { type = resource.request; }) config.resources)
       );
     };
   };
@@ -37,7 +33,7 @@ in
       description = "Collection of deployment resources that can be required by applications and policed by hosting providers";
       type = attrsOf (
         submodule (
-          { config, ... }:
+          { ... }:
           {
             _class = "fediversity-resource";
             options = {
@@ -53,12 +49,23 @@ in
                 description = "Options for configuring the resource policy for the hosting provider, a description of how the resource is made available";
                 type = deferredModuleWith {
                   staticModules = [
-                    {
+                    (policy: {
                       _class = "fediversity-resource-policy";
-                      options.apply = mkOption {
-                        desciption = "Apply the policy to a request";
+                      # 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.
+                      options.resource-type = mkOption {
+                        description = "The type of resource this policy configures";
+                        type = types.optionType;
                       };
-                    }
+                      options.apply = mkOption {
+                        description = "Apply the policy to a request";
+                        type = with types; functionTo policy.config.resource-type;
+                      };
+                    })
                   ];
                 };
               };
@@ -119,9 +126,7 @@ in
               # TODO: maybe transpose, and group the resources by type instead
               type = attrsOf (
                 attrTag (
-                  lib.mapAttrs' (name: resource: {
-                    ${name} = mkOption { type = resource.policy; };
-                  }) config.resources
+                  lib.mapAttrs (_name: resource: mkOption { type = submodule resource.policy; }) config.resources
                 )
               );
             };
@@ -140,7 +145,7 @@ in
             };
             deployment = mkOption {
               description = "Generate a deployment from a configuration";
-              type = functionTo environment.config.resource-mapping.output-type;
+              type = functionTo (submodule environment.config.resource-mapping.output-type);
               readOnly = true;
               default =
                 cfg:
@@ -161,13 +166,13 @@ in
       description = "Configuration type declaring options to be set by operators";
       type = optionType;
       readOnly = true;
-      default = submodule (configuration: {
+      default = submodule {
         options = {
           enable = lib.mkEnableOption {
             description = "your Fediversity configuration";
           };
           applications = lib.mapAttrs (
-            name: application:
+            _name: application:
             mkOption {
               description = application.description;
               type = submodule application.module;
@@ -175,7 +180,7 @@ in
             }
           ) config.applications;
         };
-      });
+      };
     };
   };
 }