1/*!
2@file
3Forward declares `boost::hana::suffix`.
4
5Copyright Louis Dionne 2013-2022
6Distributed 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_FWD_SUFFIX_HPP
11#define BOOST_HANA_FWD_SUFFIX_HPP
12
13#include <boost/hana/config.hpp>
14#include <boost/hana/core/when.hpp>
15
16
17namespace boost { namespace hana {
18 //! Inserts a value after each element of a monadic structure.
19 //! @ingroup group-MonadPlus
20 //!
21 //! Given a monadic structure `xs` and a value `z` (called the suffix),
22 //! `suffix` returns a new monadic structure such that
23 //! @code
24 //! suffix(xs, z) == flatten(transform(xs, [](auto x) {
25 //! return concat(lift<M>(x), lift<M>(z));
26 //! }))
27 //! @endcode
28 //!
29 //! For sequences, this simply corresponds to inserting the suffix after
30 //! each element of the sequence. For example, given a sequence
31 //! `[x1, ..., xn]`, `suffix` will return
32 //! @code
33 //! [x1, z, x2, z, ..., xn, z]
34 //! @endcode
35 //! As explained above, this can be generalized to other MonadPlus models,
36 //! with various levels of interest.
37 //!
38 //!
39 //! Signature
40 //! ---------
41 //! Given a MonadPlus `M`, the signature is
42 //! @f$ \mathtt{suffix} : M(T) \times T \to M(T) @f$.
43 //!
44 //! @param xs
45 //! A monadic structure.
46 //!
47 //! @param sfx
48 //! A value (the suffix) to insert after each element of a monadic
49 //! structure.
50 //!
51 //!
52 //! Example
53 //! -------
54 //! @include example/suffix.cpp
55#ifdef BOOST_HANA_DOXYGEN_INVOKED
56 constexpr auto suffix = [](auto&& xs, auto&& sfx) {
57 return tag-dispatched;
58 };
59#else
60 template <typename M, typename = void>
61 struct suffix_impl : suffix_impl<M, when<true>> { };
62
63 struct suffix_t {
64 template <typename Xs, typename Sfx>
65 constexpr auto operator()(Xs&& xs, Sfx&& sfx) const;
66 };
67
68 BOOST_HANA_INLINE_VARIABLE constexpr suffix_t suffix{};
69#endif
70}} // end namespace boost::hana
71
72#endif // !BOOST_HANA_FWD_SUFFIX_HPP
73

source code of boost/libs/hana/include/boost/hana/fwd/suffix.hpp