Conceptualize member spaceship lens.

comparisons.h

@@ -34,23 +34,17 @@ namespace Alepha::Hydrogen
 
 		// Spaceship lens support
 
-		template< typename T, typename= void >
-		struct has_spaceship_lens_member : std::false_type {};
-
 		template< typename T >
-		struct has_spaceship_lens_member< T, std::void_t< decltype( std::declval< const T & >().spaceship_lens() ) > > : std::true_type {};
+		concept MemberSpaceshipLensed=
+		LensComparable< T >
+				and
+		requires( const T &lhs, const T &rhs )
+		{
+			{ lhs.spaceship_lens() <=> rhs.spaceship_lens() } -> SameAs< std::strong_ordering >;
+		};
 
-		template< typename T >
-		constexpr bool has_spaceship_lens_member_v= has_spaceship_lens_member< T >::value;
-
-		template
-		<
-			LensComparable T,
-			typename= std::enable_if_t< has_spaceship_lens_member_v< T > >,
-			overload< __LINE__ > = nullptr
-		>
 		constexpr decltype( auto )
-		spaceship_lens( T &t )
+		spaceship_lens( const MemberSpaceshipLensed auto &t )
 		{
 			return t.spaceship_lens();
 		}