abstract_function_type.cpp

#include <functional>
#include <iostream>

template<typename T, typename... U>
using Fn = std::function<T(U...)>;

int add(int x, int y) {
  return x + y;
}

int main() {
  Fn<int,int,int> plus = add;
  std::cout << plus(1,2) << std::endl;
  return 0;
}