#include <iostream>
#include <vector>
#include <functional>

template<typename T>
void dump(std::vector<T> keys)
{
    std::wcout << L"Keys: [";
    auto isFirst = true;
    for (auto key : keys)
    {
        std::wcout << (isFirst ? L"" : L", ") << key;
        isFirst = false;
    }
    std::wcout << L"]" << std::endl;
}

template<typename T1, typename T2> using Mapper = std::function<T2(T1 item)>;

template<typename T1, typename T2>
std::vector<T2> map(const Mapper<T1, T2> mapper, const std::vector<T1> vec)
{
    std::vector<T2> result;
    for (T1 x : vec)
    {
        result.push_back(mapper(x));
    }
    return result;
}

using namespace std::placeholders;

int main()
{
    auto multiplier = 5;
    auto func = [](int n, int m)
    {
        return n * m;
    };
    std::function<int(int)> mapper = std::bind(func, _1, multiplier);
    auto list = map<int, int>(
        mapper,
        { 1, 2, 3 }
    );
    dump<int>(list);
}