hana/concept/comonad.hpp

0001 /*!
0002 @file
0003 Defines `boost::hana::Comonad`.
0004
0005 Copyright Louis Dionne 2013-2022
0006 Distributed under the Boost Software License, Version 1.0.
0007 (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
0008  */
0009
0010 #ifndef BOOST_HANA_CONCEPT_COMONAD_HPP
0011 #define BOOST_HANA_CONCEPT_COMONAD_HPP
0012
0013 #include <boost/hana/fwd/concept/comonad.hpp>
0014
0015 #include <boost/hana/config.hpp>
0016 #include <boost/hana/core/default.hpp>
0017 #include <boost/hana/core/tag_of.hpp>
0018 #include <boost/hana/detail/integral_constant.hpp>
0019 #include <boost/hana/duplicate.hpp>
0020 #include <boost/hana/extend.hpp>
0021 #include <boost/hana/extract.hpp>
0022
0023
0024 namespace boost { namespace hana {
0025     template <typename W>
0026     struct Comonad
0027         : hana::integral_constant<bool,
0028             !is_default<extract_impl<typename tag_of<W>::type>>::value &&
0029                 (!is_default<duplicate_impl<typename tag_of<W>::type>>::value ||
0030                  !is_default<extend_impl<typename tag_of<W>::type>>::value)
0031         >
0032     { };
0033 }} // end namespace boost::hana
0034
0035 #endif // !BOOST_HANA_CONCEPT_COMONAD_HPP