ceph/src/boost/libs/hana/example/optional/monad.cpp

   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/chain.hpp>
   7 #include <boost/hana/config.hpp>
   8 #include <boost/hana/equal.hpp>
   9 #include <boost/hana/flatten.hpp>
  10 #include <boost/hana/optional.hpp>
  11 namespace hana = boost::hana;
  12
  13
  14 int main() {
  15     BOOST_HANA_CONSTEXPR_LAMBDA auto inc = [](auto x) {
  16         return hana::just(x + 1);
  17     };
  18
  19     BOOST_HANA_CONSTEXPR_CHECK(hana::chain(hana::just(1), inc) == hana::just(2));
  20     BOOST_HANA_CONSTANT_CHECK(hana::chain(hana::nothing, inc) == hana::nothing);
  21
  22     BOOST_HANA_CONSTEXPR_CHECK(hana::flatten(hana::just(hana::just(2))) == hana::just(2));
  23 }