feat(registry): validate unique addresses and routes

lib/registry.nix

@@ -16,6 +16,7 @@ let
     nameValuePair
     removeSuffix
     types
+    unique
     ;
 
   assertionType = types.submodule {
@@ -36,6 +37,30 @@ let
     };
   };
 
+  validators = {
+    uniqueValue =
+      {
+        value,
+        message,
+      }:
+      entries:
+      let
+        values = map value entries;
+      in
+      [
+        {
+          assertion = builtins.length (unique values) == builtins.length values;
+          inherit message;
+        }
+      ];
+  };
+
+  registryLib = lib // {
+    registry = (lib.registry or { }) // {
+      inherit validators;
+    };
+  };
+
   registryDefinitionModule = {
     options = {
       type = mkOption {
@@ -76,7 +101,7 @@ let
   mkRegistry = path:
     let
       evaluated = lib.evalModules {
-        specialArgs = { inherit lib; };
+        specialArgs.lib = registryLib;
         modules = [
           registryDefinitionModule
           path
@@ -189,7 +214,7 @@ let
     };
 in
 {
-  inherit definitions;
+  inherit definitions validators;
 
   module = {
     options.registry = mapAttrs (_name: registry: registryOption registry) definitions;