File size: 1,263 Bytes
8ae5fc5 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 | #ifndef METAL_LAMBDA_ALWAYS_HPP
#define METAL_LAMBDA_ALWAYS_HPP
#include "../config.hpp"
namespace metal {
/// \cond
namespace detail {
template <class val>
struct _always;
}
/// \endcond
/// \ingroup lambda
///
/// ### Description
/// Lifts a \value to an n-ary \lambda that always evaluates to that \value,
/// regardless of the argument(s) it's [invoked](\ref invoke) with.
///
/// ### Usage
/// For any and \value `val`
/// \code
/// using result = metal::always<val>;
/// \endcode
///
/// \returns: \lambda
/// \semantics:
/// Equivalent to
/// \code
/// using result = metal::lambda<expr>;
/// \endcode
/// where `expr` is an \expression such that
/// \code
/// template<class...>
/// using expr = val;
/// \endcode
///
/// ### Example
/// \snippet lambda.cpp always
///
/// ### See Also
/// \see lambda, invoke, partial, bind
template <class val>
using always = typename detail::_always<val>::type;
}
#include "../lambda/lambda.hpp"
#include "../value/identity.hpp"
namespace metal {
/// \cond
namespace detail {
template <class val>
struct _always {
template <class...>
using impl = identity<val>;
using type = lambda<impl>;
};
}
/// \endcond
}
#endif
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