hana/example/ext/std/integer_sequence/foldable.cpp
2017-01-07 14:14:18 -08:00

26 lines
753 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/ext/std/integer_sequence.hpp>
#include <boost/hana/unpack.hpp>
#include <tuple>
#include <utility>
namespace hana = boost::hana;
auto add = [](auto a, auto b, auto c) { return a + b + c; };
int main() {
std::tuple<int, long, double> tuple{1, 2l, 3.3};
auto sum = hana::unpack(std::integer_sequence<int, 0, 1, 2>{}, [&](auto ...i) {
// the `i`s are `std::integral_constant<int, ...>`s
return add(std::get<decltype(i)::value>(tuple)...);
});
BOOST_HANA_RUNTIME_CHECK(sum == 6.3);
}