#include <cassert>
#include <utility>
#include <string>
#include <iostream>

struct Sentinel { };

Sentinel make_list()
{
    return { };
}

template <typename T, typename... Ts>
auto make_list(T&& first, Ts&&... rest)
{
    return std::make_pair(std::forward<T>(first),
			  make_list(std::forward<Ts>(rest)...));
}

namespace details
{
    
    template <int N, typename T>
    struct Get_Index
    {
	static auto& value(T& list)
	{
	    return Get_Index<N - 1, typename T::second_type>::value(list.second);
	}
	
    };
    
    template <typename T>
    struct Get_Index<0, T>
    {
	static auto& value(T& list)
	{
	    return list.first;
	}	
    };
    
}

template <unsigned N, typename T>
auto& get_index(T& list)
{
    return details::Get_Index<N, T>::value(list);
}

int main()
{
    std::string last { "54" };
    auto list1 = make_list(1, 2.3, '4', last);
    assert(get_index<0>(list1) == 1);
    assert(get_index<1>(list1) == 2.3);
    assert(get_index<2>(list1) == '4');
    assert(get_index<3>(list1) == "54");

    // Check that the values can be modified
    get_index<0>(list1) = 10;
    assert(get_index<0>(list1) == 10);
}