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/fold_left.hpp>
7 #include <boost/hana/tuple.hpp>
8
9 #include <sstream>
10 #include <string>
11 namespace hana = boost::hana;
12
13
__anonb477eaee0102(auto x) 14 auto to_string = [](auto x) {
15 std::ostringstream ss;
16 ss << x;
17 return ss.str();
18 };
19
main()20 int main() {
21 auto f = [=](std::string s, auto element) {
22 return "f(" + s + ", " + to_string(element) + ")";
23 };
24
25 // with an initial state
26 BOOST_HANA_RUNTIME_CHECK(
27 hana::fold_left(hana::make_tuple(2, '3', 4, 5.0), "1", f)
28 ==
29 "f(f(f(f(1, 2), 3), 4), 5)"
30 );
31
32 // without initial state
33 BOOST_HANA_RUNTIME_CHECK(
34 hana::fold_left(hana::make_tuple("1", 2, '3', 4, 5.0), f)
35 ==
36 "f(f(f(f(1, 2), 3), 4), 5)"
37 );
38 }
39