is_nothing.cpp 587 B

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  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. #include <boost/hana/assert.hpp>
  5. #include <boost/hana/not.hpp>
  6. #include <boost/hana/optional.hpp>
  7. namespace hana = boost::hana;
  8. struct undefined { };
  9. int main() {
  10. BOOST_HANA_CONSTANT_CHECK(hana::is_nothing(hana::nothing));
  11. BOOST_HANA_CONSTANT_CHECK(hana::not_(hana::is_nothing(hana::just(undefined{}))));
  12. BOOST_HANA_CONSTANT_CHECK(hana::not_(hana::is_nothing(hana::just(hana::nothing))));
  13. }