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/*!
@file
Forward declares `boost::hana::replicate`.
Copyright Louis Dionne 2013-2022
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_FWD_REPLICATE_HPP
#define BOOST_HANA_FWD_REPLICATE_HPP
#include <boost/hana/config.hpp>
#include <boost/hana/core/when.hpp>
namespace boost { namespace hana {
//! Create a monadic structure by combining a lifted value with itself
//! `n` times.
//! @ingroup group-MonadPlus
//!
//! Given a value `x`, a non-negative `IntegralConstant` `n` and the tag
//! of a monadic structure `M`, `replicate` creates a new monadic structure
//! which is the result of combining `x` with itself `n` times inside the
//! monadic structure. In other words, `replicate` simply `lift`s `x` into
//! the monadic structure, and then combines that with itself `n` times:
//! @code
//! replicate<M>(x, n) == cycle(lift<M>(x), n)
//! @endcode
//!
//! If `n` is zero, then the identity of the `concat` operation is returned.
//! In the case of sequences, this corresponds to creating a new sequence
//! holding `n` copies of `x`.
//!
//!
//! Signature
//! ---------
//! Given an `IntegralConstant` `C` and MonadPlus `M`, the signature is
//! @f$ \mathtt{replicate}_M : T \times C \to M(T) @f$.
//!
//! @tparam M
//! The tag of the returned monadic structure. It must be a
//! model of the MonadPlus concept.
//!
//! @param x
//! The value to lift into a monadic structure and then combine with
//! itself.
//!
//! @param n
//! A non-negative `IntegralConstant` representing the number of times to
//! combine `lift<M>(x)` with itself. If `n == 0`, `replicate` returns
//! `empty<M>()`.
//!
//!
//! Example
//! -------
//! @include example/replicate.cpp
#ifdef BOOST_HANA_DOXYGEN_INVOKED
template <typename M>
constexpr auto replicate = [](auto&& x, auto const& n) {
return tag-dispatched;
};
#else
template <typename M, typename = void>
struct replicate_impl : replicate_impl<M, when<true>> { };
template <typename M>
struct replicate_t {
template <typename X, typename N>
constexpr auto operator()(X&& x, N const& n) const;
};
template <typename M>
BOOST_HANA_INLINE_VARIABLE constexpr replicate_t<M> replicate{};
#endif
}} // end namespace boost::hana
#endif // !BOOST_HANA_FWD_REPLICATE_HPP
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