swap out the input types to hopefully trigger an evaluation error - unfortunately does not seem to work yet

allowed fixing a few types, tho bad input types still work, and needs
commenting readOnly

deployment/data-model-test.nix

@@ -182,6 +182,7 @@ in
           };
         deployment = {
           inherit (result) _type;
+          isModule = lib.isFunction fediversity.deployments.example.deployment;
           deploymentFunction = lib.isFunction result.deploymentFunction;
           getProviders = lib.isFunction result.getProviders;
         };
@@ -204,6 +205,7 @@ in
         _type = "nixops4Deployment";
         deploymentFunction = true;
         getProviders = true;
+        isModule = false;
       };
     };
   };

deployment/data-model.nix

@@ -108,7 +108,8 @@ in
               type = functionType;
               readOnly = true;
               default = {
-                input-type = submodule application.config.module;
+                # input-type = submodule application.config.module;
+                input-type = types.int;
                 output-type = application-resources;
               };
             };
@@ -142,9 +143,10 @@ in
             resource-mapping = mkOption {
               description = "Function type for the mapping from resources to a (NixOps4) deployment";
               type = functionType;
-              readOnly = true;
+              # readOnly = true;
               default = {
-                input-type = application-resources;
+                # input-type = application-resources;
+                input-type = types.int;
                 output-type = nixops4Deployment;
               };
             };

deployment/function.nix

@@ -20,7 +20,7 @@ submodule (function: {
     };
     function-type = mkOption {
       type = optionType;
-      readOnly = true;
+      # readOnly = true;
       default = functionTo (submodule {
         options = {
           input = mkOption {