text: // Copyright Louis Dionne 2013-2017
  // Distributed under the Boost Software License, Version 1.0.
  // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
  
  #include <boost/hana/assert.hpp>
  #include <boost/hana/equal.hpp>
  #include <boost/hana/plus.hpp>
  #include <boost/hana/string.hpp>
  namespace hana = boost::hana;
  
  
  int main() {
      BOOST_HANA_CONSTANT_CHECK(hana::equal(
          hana::plus(BOOST_HANA_STRING(""), BOOST_HANA_STRING("")),
          BOOST_HANA_STRING("")
      ));
      BOOST_HANA_CONSTANT_CHECK(hana::equal(
          hana::plus(BOOST_HANA_STRING("abcd"), BOOST_HANA_STRING("")),
          BOOST_HANA_STRING("abcd")
      ));
      BOOST_HANA_CONSTANT_CHECK(hana::equal(
          hana::plus(BOOST_HANA_STRING(""), BOOST_HANA_STRING("abcd")),
          BOOST_HANA_STRING("abcd")
      ));
      BOOST_HANA_CONSTANT_CHECK(hana::equal(
          hana::plus(BOOST_HANA_STRING("abcd"), BOOST_HANA_STRING("efg")),
          BOOST_HANA_STRING("abcdefg")
      ));
  
      // check operator
      BOOST_HANA_CONSTANT_CHECK(hana::equal(
          BOOST_HANA_STRING("abc") + BOOST_HANA_STRING("def"),
          BOOST_HANA_STRING("abcdef")
      ));
  }
  