diff --git a/TODO b/TODO
index 72f4bfa6a..e728160ab 100644
--- a/TODO
+++ b/TODO
@@ -26,4 +26,4 @@
 * hashed string: static (constexpr) member function to_value for direct hashing
 * entity: simplify get functions so as to generate less symbols for multiple components
 * events on replace, so that one can track updated components? indagate impact
-* add merge functionality for type list
+* allow to bind values to delegate on connect with free functions (sbo + check size on costruction to guarantee a zero allocation abstraction)
diff --git a/src/entt/core/type_traits.hpp b/src/entt/core/type_traits.hpp
index 99e6b48eb..c37716b80 100644
--- a/src/entt/core/type_traits.hpp
+++ b/src/entt/core/type_traits.hpp
@@ -10,6 +10,30 @@ template<typename...>
 struct type_list {};
 
 
+/**
+ * @brief Concatenates multiple type lists into one.
+ * @tparam Type List of types.
+ * @return The given type list.
+ */
+template<typename... Type>
+constexpr auto type_list_cat(type_list<Type...> = type_list<>{}) {
+    return type_list<Type...>{};
+}
+
+
+/**
+ * @brief Concatenates multiple type lists into one.
+ * @tparam Type List of types.
+ * @tparam Other List of types.
+ * @tparam List Type list instances.
+ * @return A type list that is the concatenation of the given type lists.
+ */
+template<typename... Type, typename... Other, typename... List>
+constexpr auto type_list_cat(type_list<Type...>, type_list<Other...>, List...) {
+    return type_list_cat(type_list<Type..., Other...>{}, List{}...);
+}
+
+
 }
 
 
diff --git a/src/entt/entity/registry.hpp b/src/entt/entity/registry.hpp
index de9c7463a..b92768faf 100644
--- a/src/entt/entity/registry.hpp
+++ b/src/entt/entity/registry.hpp
@@ -1161,7 +1161,7 @@ public:
      * @return A newly created persistent view.
      */
     template<typename... Component, typename... Exclude>
-    entt::persistent_view<Entity, Component...> persistent_view(type_list<Exclude...> = type_list<>{}) {
+    entt::persistent_view<Entity, Component...> persistent_view(type_list<Exclude...> = {}) {
         static_assert(sizeof...(Component));
         using handler_type = handler_pool<type_list<Component...>, type_list<Exclude...>>;
         const auto htype = handler_family::type<Component...>;
@@ -1196,7 +1196,7 @@ public:
 
     /*! @copydoc persistent_view */
     template<typename... Component, typename... Exclude>
-    inline entt::persistent_view<Entity, Component...> persistent_view(type_list<Exclude...> = type_list<>{}) const {
+    inline entt::persistent_view<Entity, Component...> persistent_view(type_list<Exclude...> = {}) const {
         static_assert(std::conjunction_v<std::is_const<Component>...>);
         return const_cast<registry *>(this)->persistent_view<Component...>(type_list<Exclude...>{});
     }
@@ -1294,7 +1294,7 @@ public:
      * @param reg A valid reference to a source registry.
      */
     template<typename... Component>
-    void clone(const registry &reg) {
+    void clone(const registry &reg, type_list<Component...> = {}) {
         *this = {};
 
         (assure<Component>(), ...);
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index eb3e37bb2..4776d5982 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -63,6 +63,7 @@ SETUP_AND_ADD_TEST(family entt/core/family.cpp)
 SETUP_AND_ADD_TEST(hashed_string entt/core/hashed_string.cpp)
 SETUP_AND_ADD_TEST(ident entt/core/ident.cpp)
 SETUP_AND_ADD_TEST(monostate entt/core/monostate.cpp)
+SETUP_AND_ADD_TEST(type_traits entt/core/type_traits.cpp)
 SETUP_AND_ADD_TEST(utility entt/core/utility.cpp)
 
 # Test entity
diff --git a/test/entt/core/type_traits.cpp b/test/entt/core/type_traits.cpp
new file mode 100644
index 000000000..ef77c1330
--- /dev/null
+++ b/test/entt/core/type_traits.cpp
@@ -0,0 +1,22 @@
+#include <type_traits>
+#include <gtest/gtest.h>
+#include <entt/core/type_traits.hpp>
+
+TEST(TypeTraits, TypeList) {
+    static_assert(std::is_same_v<
+        decltype(entt::type_list_cat()),
+        entt::type_list<>
+    >);
+
+    static_assert(std::is_same_v<
+        decltype(entt::type_list_cat(entt::type_list<int>{})),
+        entt::type_list<int>
+    >);
+
+    static_assert(std::is_same_v<
+        decltype(entt::type_list_cat(entt::type_list<int, char>{}, entt::type_list<>{}, entt::type_list<double, void>{})),
+        entt::type_list<int, char, double, void>
+    >);
+
+    SUCCEED();
+}
diff --git a/test/mod/mod.cpp b/test/mod/mod.cpp
index eae29eb7b..e81bb29cd 100644
--- a/test/mod/mod.cpp
+++ b/test/mod/mod.cpp
@@ -127,13 +127,11 @@ class duktape_registry {
 
     struct func_map {
         using func_type = duk_ret_t(*)(duk_context *, entt::registry<> &);
-        using test_type = bool(entt::registry<>:: *)(entt::registry<>::entity_type) const;
 
         func_type set;
         func_type unset;
         func_type has;
         func_type get;
-        test_type test;
     };
 
     template<typename... Comp>
@@ -142,8 +140,7 @@ class duktape_registry {
                 &::set<Comp>,
                 &::unset<Comp>,
                 &::has<Comp>,
-                &::get<Comp>,
-                &entt::registry<>::has<Comp>
+                &::get<Comp>
         }), ...);
     }