#include <boost/hana/value.hpp>
-BOOST_HANA_NAMESPACE_BEGIN
+namespace boost { namespace hana {
template <typename C>
struct Constant
: hana::integral_constant<bool,
!is_default<value_impl<typename tag_of<C>::type>>::value
>
{ };
-BOOST_HANA_NAMESPACE_END
+}} // end namespace boost::hana
#endif // !BOOST_HANA_CONCEPT_CONSTANT_HPP