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/concat.hpp> 7 #include <boost/hana/empty.hpp> 8 #include <boost/hana/equal.hpp> 9 #include <boost/hana/optional.hpp> 10 namespace hana = boost::hana; 11 12 13 static_assert(hana::concat(hana::nothing, hana::just('x')) == hana::just('x'), ""); 14 BOOST_HANA_CONSTANT_CHECK(hana::concat(hana::nothing, hana::nothing) == hana::nothing); 15 static_assert(hana::concat(hana::just('x'), hana::just('y')) == hana::just('x'), ""); 16 BOOST_HANA_CONSTANT_CHECK(hana::empty<hana::optional_tag>() == hana::nothing); 17 main()18int main() { } 19