1 // Copyright Louis Dionne 2013-2017 2 // Distributed under the Boost Software License, Version 1.0. 3 // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt) 4 5 #include <boost/hana/assert.hpp> 6 #include <boost/hana/not.hpp> 7 #include <boost/hana/optional.hpp> 8 namespace hana = boost::hana; 9 10 11 struct undefined { }; 12 main()13int main() { 14 BOOST_HANA_CONSTANT_CHECK(hana::is_nothing(hana::nothing)); 15 BOOST_HANA_CONSTANT_CHECK(hana::not_(hana::is_nothing(hana::just(undefined{})))); 16 BOOST_HANA_CONSTANT_CHECK(hana::not_(hana::is_nothing(hana::just(hana::nothing)))); 17 } 18