A bunch of handy metafunctions from my ISO scratch work.

This has to be put into the hierarchy right, but that can come later.

meta.h

@@ -0,0 +1,77 @@
+static_assert( __cplusplus > 2020'00 );
+
+#pragma once
+
+#include <type_traits>
+#include <tuple>
+#include <vector>
+#include <deque>
+#include <list>
+#include <array>
+#include <optional>
+#include <functional>
+#include <string_view>
+
+//#include "meta_matching.hpp"
+
+#include "type_lisp.h"
+
+namespace Alepha::inline Cavorite  ::detail::  meta
+{
+	inline namespace exports
+	{
+		template< auto q, typename >
+		constexpr decltype( q ) dependent_value= q;
+
+		template< typename T >
+		constexpr bool is_array_v= false;
+
+		template< typename T, std::size_t sz >
+		constexpr bool is_array_v< std::array< T, sz > >{ true };
+
+		template< typename T, template< typename ... > class Ref >
+		constexpr bool is_specialization_of_v= false;
+
+		template< template< typename ... > class Ref, typename ... Args >
+		constexpr bool is_specialization_of_v< Ref< Args... >, Ref >{ true };
+
+		template< typename T, typename ... Member >
+		constexpr bool is_specialized_on_v= false;
+
+		template< template< typename ... > class Base, typename Member >
+		constexpr bool is_specialized_on_v< Base< Member >, Member >{ true };
+
+		template< typename T >
+		concept is_functional_v=
+		requires( const T &t )
+		{
+			{ std::function( t ) };
+		};
+
+		template< typename T >
+		constexpr bool is_pair_v= is_specialization_of_v< T, std::pair >;
+
+		template< typename T >
+		constexpr bool is_tuple_v= is_specialization_of_v< T, std::tuple >;
+
+		template< typename T >
+		struct decay_tuple;
+
+		template< typename ... Args >
+		struct decay_tuple< std::tuple< Args... > >
+		{
+			using type= std::tuple< std::decay_t< Args >... >;
+		};
+
+		template< typename T >
+		using decay_tuple_t= typename decay_tuple< T >::type;
+
+		template< typename T >
+		constexpr bool is_optional_v= is_specialization_of_v< T, std::optional >;
+	}
+}
+
+namespace Alepha::inline Cavorite::inline exports::inline meta
+{
+	using namespace detail::meta::exports;
+}