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hana/example/list/foldable/foldl.cpp
2014-06-05 22:47:39 -04:00

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1.1 KiB
C++

/*
@copyright Louis Dionne 2014
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/detail/constexpr.hpp>
#include <boost/hana/detail/static_assert.hpp>
#include <boost/hana/integral.hpp>
#include <boost/hana/list.hpp>
#include <boost/hana/logical.hpp>
#include <boost/hana/trait.hpp>
#include <boost/hana/type.hpp>
#include <cassert>
#include <sstream>
#include <string>
using namespace boost::hana;
int main() {
//! [fusion]
auto make_string = [](std::string str, auto x) {
return str + (std::ostringstream{} << x).str();
};
assert(foldl(make_string, "1", list(2, "3", '4')) == "1234");
//! [fusion]
//! [mpl]
BOOST_HANA_CONSTEXPR_LAMBDA auto types = list_t<long, float, short, double, float, long, long double>;
BOOST_HANA_CONSTEXPR_LAMBDA auto count_if_float = [](auto c, auto t) {
return if_(trait::is_floating_point(t), c + int_<1>, c);
};
BOOST_HANA_STATIC_ASSERT(foldl(count_if_float, int_<0>, types) == int_<4>);
//! [mpl]
}