hana/example/optional/monad.cpp
2017-01-07 14:14:18 -08:00

24 lines
780 B
C++

// 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/chain.hpp>
#include <boost/hana/config.hpp>
#include <boost/hana/equal.hpp>
#include <boost/hana/flatten.hpp>
#include <boost/hana/optional.hpp>
namespace hana = boost::hana;
int main() {
BOOST_HANA_CONSTEXPR_LAMBDA auto inc = [](auto x) {
return hana::just(x + 1);
};
BOOST_HANA_CONSTEXPR_CHECK(hana::chain(hana::just(1), inc) == hana::just(2));
BOOST_HANA_CONSTANT_CHECK(hana::chain(hana::nothing, inc) == hana::nothing);
BOOST_HANA_CONSTEXPR_CHECK(hana::flatten(hana::just(hana::just(2))) == hana::just(2));
}