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// 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/eval.hpp>
#include <boost/hana/extend.hpp>
#include <boost/hana/extract.hpp>
#include <boost/hana/lazy.hpp>
#include <sstream>
namespace hana = boost::hana;
int main() {
std::stringstream s("1 2 3");
auto i = hana::make_lazy([&] {
int i;
s >> i;
return i;
})();
auto i_plus_one = hana::extend(i, [](auto lazy_int) {
return hana::eval(lazy_int) + 1;
});
BOOST_HANA_RUNTIME_CHECK(hana::extract(i_plus_one) == 2);
BOOST_HANA_RUNTIME_CHECK(hana::extract(i_plus_one) == 3);
BOOST_HANA_RUNTIME_CHECK(hana::extract(i_plus_one) == 4);
}
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