1 /*!
2 @file
3 Defines operators for Monads.
4 
5 @copyright Louis Dionne 2013-2017
6 Distributed under the Boost Software License, Version 1.0.
7 (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
8  */
9 
10 #ifndef BOOST_HANA_DETAIL_OPERATORS_MONAD_HPP
11 #define BOOST_HANA_DETAIL_OPERATORS_MONAD_HPP
12 
13 #include <boost/hana/config.hpp>
14 #include <boost/hana/core/tag_of.hpp>
15 #include <boost/hana/fwd/chain.hpp>
16 
17 #include <type_traits>
18 
19 
20 BOOST_HANA_NAMESPACE_BEGIN namespace detail {
21     template <typename Tag>
22     struct monad_operators {
23         static constexpr bool value = false;
24     };
25 
26     namespace operators {
27         template <typename Xs, typename F, typename = typename std::enable_if<
28             detail::monad_operators<typename hana::tag_of<Xs>::type>::value
29         >::type>
operator |(Xs && xs,F && f)30         constexpr auto operator|(Xs&& xs, F&& f)
31         { return hana::chain(static_cast<Xs&&>(xs), static_cast<F&&>(f)); }
32     } // end namespace operators
33 } BOOST_HANA_NAMESPACE_END
34 
35 #endif // !BOOST_HANA_DETAIL_OPERATORS_MONAD_HPP
36