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Is it possible to emulate the type class functionality of Haskell with C++ (or C#) templates? Does it make sense or is there any payoff in doing that? I was trying to make a Functor class in C++ and I wasn't able. I tried something like this: #include <iostream> using namespace std; //A function class to make types more readable template <class input, class output> class Function { private: output (*ptrfunc )(input); public: Function(output (* ptr)(input)) { ptrfunc = ptr; } output call(input x) {return (*ptrfunc)(x);} output operator() (input x) { return call(x);} }; //the functor "typeclass" template <class a> class Functor{ public: template <class b> Functor<b> fmap(Function<a,b> func); }; // an container type to be declared "instance" of functor: template <class a> class List : public Functor<a> { private: a * ptrList; int size; public: List(int n) { //constructor; ptrList = new a[n]; size = n; } List(List<a> const& other) { //copy constructor size = other.size; ptrList = new a[size]; for(int i = 0; i<size; i++) (*this)[i] = other[i]; } ~List() { delete ptrList;} //destructor a& operator[](int i) { return ptrList[i];} // subscript operator just for easy notation const a& operator[](int i) const { return ptrList[i];}// subscript operator just for easy notation template <class b> List<b> fmap(Function<a,b> func) { //"instance" version of fmap List<b> temp(size); for(int i = 0; i < size; i++) temp[i] = func((*this)[i]); return temp; } }; int test(int k) { return 2 * k;} int main(void) { Function<int, int> func(&test); List<int> lista(10); for(int i = 0; i < 10; i++) lista[i] = i; List<int> lista2(lista.fmap(func)); for(int i = 0; i < 10; i++) cout << lista2[i] << " "; cout <

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