feat update

#pragma once

#include "sled/any.h"

#include <functional>

#include <string>

namespace sled {

namespace failure {

namespace {

template<typename F, typename... Args>

struct is_invocable : std::is_constructible<std::function<void(Args...)>,

                                            std::reference_wrapper<typename std::remove_reference<F>::type>> {};

}// namespace

template<typename FailureT>

inline FailureT

FailureFromString(std::string &&)

    return std::move(str);

}

template<typename FailureT,

         typename = typename std::enable_if<std::is_constructible<FailureT, std::string>::value>::type>

inline FailureT

FailureFromString(std::string &&str)

{

    return FailureT(std::move(str));

}

}// namespace failure

namespace future_detail {