/*! @file Forward declares `boost::hana::replicate`. @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_FWD_REPLICATE_HPP #define BOOST_HANA_FWD_REPLICATE_HPP #include <boost/hana/config.hpp> #include <boost/hana/core/when.hpp> BOOST_HANA_NAMESPACE_BEGIN //! 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 M> constexpr replicate_t<M> replicate{}; #endif BOOST_HANA_NAMESPACE_END #endif // !BOOST_HANA_FWD_REPLICATE_HPP