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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/fold_left.hpp>
- #include <boost/hana/tuple.hpp>
- #include <sstream>
- #include <string>
- namespace hana = boost::hana;
- auto to_string = [](auto x) {
- std::ostringstream ss;
- ss << x;
- return ss.str();
- };
- int main() {
- auto f = [=](std::string s, auto element) {
- return "f(" + s + ", " + to_string(element) + ")";
- };
- // with an initial state
- BOOST_HANA_RUNTIME_CHECK(
- hana::fold_left(hana::make_tuple(2, '3', 4, 5.0), "1", f)
- ==
- "f(f(f(f(1, 2), 3), 4), 5)"
- );
- // without initial state
- BOOST_HANA_RUNTIME_CHECK(
- hana::fold_left(hana::make_tuple("1", 2, '3', 4, 5.0), f)
- ==
- "f(f(f(f(1, 2), 3), 4), 5)"
- );
- }
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