diff --git a/source/coral.cpp b/source/coral.cpp
index 27e163e..3edd14f 100644
--- a/source/coral.cpp
+++ b/source/coral.cpp
@@ -3,6 +3,7 @@ module;
 #include <cstdint>
 #include <cstddef>
 #include <type_traits>
+#include <concepts>
 
 export module coral;
 
@@ -285,6 +286,15 @@ export void operator delete[](void * pointer, coral::allocator & allocator) {
 
 // Wrapper types.
 export namespace coral {
+	template<typename type, typename... arguments> concept function_pointer = requires (type value, arguments... value_arguments) {
+		{*value};
+		{value(value_arguments...)};
+	};
+
+	template<typename type, typename... arguments> concept functor = requires (type value, arguments... value_arguments) {
+		{value.operator()(value_arguments...)};
+	};
+
 	template<typename> struct closure;
 
 	/**
@@ -295,42 +305,32 @@ export namespace coral {
 	 * the caller to manage the lifetime of any functor assigned to it.
 	 */
 	template<typename returns, typename... arguments> struct closure<returns(arguments...)> {
-		using function = returns(*)(arguments...);
-
-		closure(function callable_function) {
-			this->dispatch = [](void const * context, arguments... dispatch_arguments) -> returns {
-				return (reinterpret_cast<function const *>(context))(dispatch_arguments...);
+		template<typename callable> closure(callable const & call) requires function_pointer<callable, arguments...> {
+			this->dispatch = [](void * context, arguments... dispatch_arguments) -> returns {
+				return (*reinterpret_cast<callable *>(context))(dispatch_arguments...);
 			};
 
-			this->context = callable_function;
+			this->context = reinterpret_cast<void *&>(call);
 		}
 
-		template<typename functor> closure(functor * callable_functor) {
-			this->dispatch = [](void const * context, arguments... dispatch_arguments) -> returns {
-				return (*reinterpret_cast<functor const*>(context))(dispatch_arguments...);
+		template<typename callable> closure(callable && call) requires functor<callable, arguments...> {
+			this->dispatch = [](void * context, arguments... dispatch_arguments) -> returns {
+				return (*reinterpret_cast<callable *>(context))(dispatch_arguments...);
 			};
 
-			this->context = callable_functor;
+			this->context = &call;
 		}
 
 		closure(closure const &) = delete;
 
-		template<typename functor> closure(functor && callable_functor) {
-			this->dispatch = [](void const * context, arguments... dispatch_arguments) -> returns {
-				return (*reinterpret_cast<functor const*>(context))(dispatch_arguments...);
-			};
-
-			this->context = &callable_functor;
-		}
-
 		returns operator()(arguments const &... call_arguments) const {
 			return this->dispatch(this->context, call_arguments...);
 		}
 
 		private:
-		void const * context;
+		void * context;
 
-		returns(* dispatch)(void const *, arguments...);
+		returns(* dispatch)(void *, arguments...);
 	};
 
 	/**