try to modularly apply functions, hoping to fix input type checks

fix types

deployment/data-model-test.nix

@@ -13,7 +13,6 @@ let
         ./data-model.nix
       ];
     }).config;
-  nixops4Deployment = inputs.nixops4.modules.nixops4Deployment.default;
   inherit (inputs.nixops4.lib) mkDeployment;
 in
 {
@@ -134,6 +133,10 @@ in
                       };
                   };
                 };
+              deployments.example = {
+                environment = config.environments.single-nixos-vm;
+                configuration = config.example-configuration;
+              };
             };
             options = {
               example-configuration = mkOption {
@@ -144,27 +147,27 @@ in
                   applications.hello.enable = true;
                 };
               };
-              example-deployment = mkOption {
-                type = types.submodule nixops4Deployment;
-                readOnly = true;
-                default = config.environments.single-nixos-vm.deployment config.example-configuration;
-              };
             };
           }
         );
-        resources = fediversity.applications.hello.resources fediversity.example-configuration.applications.hello;
+        resources = fediversity.example-configuration.required-resources.hello;
         hello-shell = resources.resources.hello.login-shell;
         environment = fediversity.environments.single-nixos-vm.resources.operator-environment.login-shell;
         result = mkDeployment {
           modules = [
-            (fediversity.environments.single-nixos-vm.deployment fediversity.example-configuration)
+            fediversity.deployments.example.deployment
           ];
         };
 
       in
       {
         number-of-resources = with lib; length (attrNames fediversity.resources);
-        inherit (fediversity) example-configuration;
+        # XXX: nix-unit unlike nix-build seems to hit infinite recursions on
+        # evaluation of package paths, so we avoid evaluating
+        # fediversity.example-configuration.required-resources.hello.resources.hello.login-shell.packages.hello
+        example-configuration = {
+          inherit (fediversity.example-configuration) enable applications;
+        };
         hello-package-exists = hello-shell.packages ? hello;
         wheel-required = hello-shell.wheel;
         wheel-allowed = environment.wheel;

deployment/data-model.nix

@@ -1,6 +1,7 @@
 {
   lib,
   config,
+  options,
   inputs,
   ...
 }:
@@ -15,7 +16,7 @@ let
     functionTo
     ;
 
-  functionType = import ./function.nix;
+  functionType = import ./function.nix { inherit lib; };
   application-resources = submodule {
     options.resources = mkOption {
       # TODO: maybe transpose, and group the resources by type instead
@@ -101,16 +102,10 @@ in
               description = "Mapping of application configuration to deployment resources, a description of what an application needs to run";
               type = application.config.config-mapping.function-type;
             };
-            resources = mkOption {
-              description = "Compute resources required by an application";
-              type = functionTo application.config.config-mapping.output-type;
-              readOnly = true;
-              default = input: (application.config.implementation input).output;
-            };
             # TODO(@fricklerhandwerk): this needs a better name, it's just the type
             config-mapping = mkOption {
               description = "Function type for the mapping from application configuration to required resources";
-              type = submodule functionType;
+              type = functionType;
               readOnly = true;
               default = {
                 input-type = submodule application.config.module;
@@ -146,31 +141,13 @@ in
             };
             resource-mapping = mkOption {
               description = "Function type for the mapping from resources to a (NixOps4) deployment";
-              type = submodule functionType;
+              type = functionType;
               readOnly = true;
               default = {
                 input-type = application-resources;
                 output-type = nixops4Deployment;
               };
             };
-            # TODO(@fricklerhandwerk): maybe this should be a separate thing such as `fediversity-setup`,
-            # which makes explicit which applications and environments are available.
-            # then the deployments can simply be the result of the function application baked into this module.
-            deployment = mkOption {
-              description = "Generate a deployment from a configuration, by applying an environment's resource policies to the applications' resource mappings";
-              type = functionTo (environment.config.resource-mapping.output-type);
-              readOnly = true;
-              default =
-                cfg:
-                # TODO: check cfg.enable.true
-                let
-                  required-resources = lib.mapAttrs (
-                    name: application-settings: config.applications.${name}.resources application-settings
-                  ) cfg.applications;
-                in
-                (environment.config.implementation required-resources).output;
-
-            };
           };
         })
       );
@@ -179,7 +156,7 @@ in
       description = "Configuration type declaring options to be set by operators";
       type = optionType;
       readOnly = true;
-      default = submodule {
+      default = submodule (configuration: {
         options = {
           enable = lib.mkEnableOption {
             description = "your Fediversity configuration";
@@ -192,8 +169,55 @@ in
               default = { };
             }
           ) config.applications;
+          required-resources = mkOption {
+            description = "The deployment's required resources by application";
+            type = submodule {
+              options = lib.mapAttrs (
+                name: _application:
+                mkOption {
+                  description = "Resources required for ${name}";
+                  type = config.applications.${name}.config-mapping.output-type;
+                }
+              ) config.applications;
+            };
+            readOnly = true;
+            default = lib.mapAttrs (
+              # FIXME: in nix-unit invoking the implementation somehow triggers an infinite recursion,
+              # tho my trace statements so far got triggered just once
+              name: application-settings: (config.applications.${name}.implementation application-settings).output
+            ) configuration.config.applications;
+          };
         };
-      };
+      });
+    };
+    deployments = mkOption {
+      description = "Deployment of a configuration of applications to a run-time environment.";
+      type = attrsOf (
+        submodule (deployment: {
+          options = {
+            configuration = mkOption {
+              description = "Configuration to be deployed";
+              type = config.configuration;
+            };
+            environment = mkOption {
+              description = "The run-time environment to deploy to";
+              type = options.environments.type.nestedTypes.elemType;
+            };
+            # TODO(@fricklerhandwerk): maybe this should be a separate thing such as `fediversity-setup`,
+            # which makes explicit which applications and environments are available.
+            # then the deployments can simply be the result of the function application baked into this module.
+            deployment = mkOption {
+              description = "Generate a deployment from a configuration, by applying an environment's resource policies to the applications' resource mappings";
+              type = deployment.config.environment.resource-mapping.output-type;
+              readOnly = true;
+              # TODO: check cfg.enable.true
+              default =
+                (deployment.config.environment.implementation deployment.config.configuration.required-resources)
+                .output;
+            };
+          };
+        })
+      );
     };
   };
 }

deployment/function.nix

@@ -1,7 +1,7 @@
 /**
   Modular function type
 */
-{ config, lib, ... }:
+{ lib, ... }:
 let
   inherit (lib) mkOption types;
   inherit (types)
@@ -10,7 +10,7 @@ let
     optionType
     ;
 in
-{
+submodule (function: {
   options = {
     input-type = mkOption {
       type = optionType;
@@ -24,13 +24,13 @@ in
       default = functionTo (submodule {
         options = {
           input = mkOption {
-            type = config.input-type;
+            type = function.config.input-type;
           };
           output = mkOption {
-            type = config.output-type;
+            type = function.config.output-type;
           };
         };
       });
     };
   };
-}
+})