#include <iostream>
#include <tuple>

// Int2Type

template <int v>
struct Int2Type {
    const static int value= v;
};

// a few class templates

struct ApplyId{
    template<typename T>
    struct apply{
      typedef Int2Type<T::value> type;
    };
};

struct MakeTen{
    template<typename T>
    struct apply{
      typedef Int2Type<10> type;
    };
};

struct DoubleMe{
    template<typename T>
    struct apply{
      typedef Int2Type<2*(T::value)> type;
    };
};

struct AbsMe{
    template<typename T>
    struct apply{
      typedef Int2Type< (T::value > 0)? T::value : -(T::value) > type;
    };
};

// helper function for output

template< typename head >
void showMe( std::tuple< head> ){
  std::cout << head::value << "\n";
};

template< typename head, typename ... tail>
void showMe( std::tuple< head, tail ... > ){
  std::cout << head::value << " ," ;
  showMe( std::tuple< tail ...>() );
}

// map function

template<typename F, typename ... Elements> struct map;

template< typename F, typename ... Elements>
struct map<F,std::tuple<Elements ...> >{
    typedef std::tuple<typename F::template apply<Elements>::type ... > type;
};

int main(){

    std::cout << "original tupel: " << std::endl;
    typedef std::tuple<Int2Type<-5>,Int2Type<-4>,Int2Type<-3>,Int2Type<-2>,Int2Type<-1>,Int2Type<0>,
                       Int2Type<1>,Int2Type<2>,Int2Type<3>,Int2Type<4>,Int2Type<5> >constNumbers;
    showMe( constNumbers() );

    std::cout << "\napply identity: " << std::endl;
    typedef map<ApplyId, constNumbers >::type idConstNumbers;
    showMe( idConstNumbers() );

    std::cout << "\nset each value to 10" << std::endl;
    typedef map<MakeTen, constNumbers >::type makeTenConstNumbers;
    showMe( makeTenConstNumbers() );

    std::cout << "\ndouble each value" << std::endl;
    typedef map<DoubleMe, constNumbers >::type doubleMeConstNumbers;
    showMe( doubleMeConstNumbers() );

    std::cout << "\nabsolute value" << std::endl;
    typedef map<AbsMe, constNumbers >::type absMeConstNumbers;
    showMe( absMeConstNumbers() );

};