#include <type_traits>

template< typename... >
struct TypeList {
    using Empty = wibble::Unit;
    static constexpr size_t length = 0;
};

template< typename _T, typename... _Ts >
struct TypeList< _T, _Ts... >  : private TypeList< _Ts... > {
    using Head = _T;
    using Tail = TypeList< _Ts... >;
    static constexpr size_t length = 1 + Tail::length;
};