/*! @file Defines `boost::hana::Foldable`. @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) */ #ifndef BOOST_HANA_CONCEPT_FOLDABLE_HPP #define BOOST_HANA_CONCEPT_FOLDABLE_HPP #include <boost/hana/fwd/concept/foldable.hpp> #include <boost/hana/config.hpp> #include <boost/hana/core/default.hpp> #include <boost/hana/core/tag_of.hpp> #include <boost/hana/detail/integral_constant.hpp> #include <boost/hana/fold_left.hpp> #include <boost/hana/unpack.hpp> BOOST_HANA_NAMESPACE_BEGIN template <typename T> struct Foldable : hana::integral_constant<bool, !is_default<fold_left_impl<typename tag_of<T>::type>>::value || !is_default<unpack_impl<typename tag_of<T>::type>>::value > { }; BOOST_HANA_NAMESPACE_END #endif // !BOOST_HANA_CONCEPT_FOLDABLE_HPP