Convert a Lambda to std::function e.g. for currying

lamda2stdFunc.cpp

#include <iostream>
#include <functional>
#include <memory>
#include <iterator>
#include <algorithm>

using namespace std;

template<typename T>
struct memfun_type
{
    using type = void;
};

template<typename Ret, typename Class, typename... Args>
struct memfun_type<Ret(Class::*)(Args...) const>
{
    using type = std::function<Ret(Args...)>;
};

template<typename F>
typename memfun_type<decltype(&F::operator())>::type
FFL(F const &func)
{
  // Function from lambda !
  return func;
}

template <typename R, typename... Args> 
void Callback(std::function<R(Args...)> f)
{
    // store f and call later
    std::cout << "invoking callback.." << endl;
    cout << f(2, 3) << endl;
}

auto sub = FFL([](int a, int b)
{
    return a - b;
});

class Person {
  public:
  std::string name;
  Person(const char* szName) : name(szName) {}
  
  void printName(){
    std::cout << name << std::endl;
  }
};

std::function<void()> printSomeName;

std::vector<int> v1 {1, 2, 5, 5, 5, 9};
std::vector<int> v2 {2, 5, 7};
std::vector<int> diff;



int main()
{
    Callback(FFL([](int a, float b)
    {
        return a + b;
    }));
    
    std::cout << "3 - 10 = " << sub(3, 10) << std::endl;
    
    
    Person p("A nice person");
    
    printSomeName = std::bind(&Person::printName, p);
    
    printSomeName();
 
    return 0;
}