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/*!
@file
Defines `boost::hana::monadic_compose`.
@copyright Louis Dionne 2013-2016
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_MONADIC_COMPOSE_HPP
#define BOOST_HANA_MONADIC_COMPOSE_HPP
#include <boost/hana/fwd/monadic_compose.hpp>
#include <boost/hana/chain.hpp>
#include <boost/hana/concept/monad.hpp>
#include <boost/hana/config.hpp>
#include <boost/hana/core/dispatch.hpp>
#include <boost/hana/functional/partial.hpp>
BOOST_HANA_NAMESPACE_BEGIN
namespace detail {
struct monadic_compose_helper {
template <typename F, typename G, typename X>
constexpr decltype(auto) operator()(F&& f, G&& g, X&& x) const {
using M = typename hana::tag_of<decltype(g(x))>::type;
#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
static_assert(hana::Monad<M>::value,
"hana::monadic_compose(f, g) requires 'g' to return a monadic value");
#endif
return hana::chain(static_cast<G&&>(g)(static_cast<X&&>(x)),
static_cast<F&&>(f));
}
};
}
//! @cond
template <typename F, typename G>
constexpr auto monadic_compose_t::operator()(F&& f, G&& g) const {
return hana::partial(detail::monadic_compose_helper{},
static_cast<F&&>(f),
static_cast<G&&>(g)
);
}
//! @endcond
BOOST_HANA_NAMESPACE_END
#endif // !BOOST_HANA_MONADIC_COMPOSE_HPP
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