diff options
Diffstat (limited to 'boost/hana/monadic_compose.hpp')
-rw-r--r-- | boost/hana/monadic_compose.hpp | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/boost/hana/monadic_compose.hpp b/boost/hana/monadic_compose.hpp new file mode 100644 index 0000000000..5bd8c5b8e4 --- /dev/null +++ b/boost/hana/monadic_compose.hpp @@ -0,0 +1,51 @@ +/*! +@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 |