Code and errors

Grayhill61C.h:
--------------------------------------
#ifndef GRAYHILL61C_H
#define GRAYHILL61C_H

#include "Arduino.h"

// Generic definition of the function type
template <typename F>
class function;

// R: return type
// Args: Any arguments a function can take
template <typename R, typename... Args>
class function<R(Args...)> {
 public:
  // Type definition of the equivalent C function pointer
  using function_type = R (*)(Args...);

  // Constructor: store the function pointer
  function(function_type f) : function_ptr(f){};

  // Call operator: calls the function object like a normal function
  // PS: This version does not do perfect forwarding.
  R operator()(Args... args) { return function_ptr(args...); }

 private:
  function_type function_ptr;
};

// A helper function can be used to infer types!
template <typename R, typename... Args>
function<R(Args...)> make_function(R (*f)(Args...)) {
  return {f};
}

class Grayhill61C {
    int OutputA, OutputB, rotationCount, rotationDir, oldA, oldB, previousPinChange;
    function<void()> increment;
    function<void()> changeDirection;
  public:
    Grayhill61C(int, int, function<void()>, function<void()>);
    ~Grayhill61C();
    void tick();
};

#endif
--------------------------------------
Beginning of Grayhill61C.cpp:
--------------------------------------
#include "Grayhill61C.h"

Grayhill61C::Grayhill61C(
    int oa,
    int ob,
    function<void()> iIncrement,
    function<void()> iChangeDirection
  ) {
  OutputA = oa;
  OutputB = ob;
  increment = iIncrement;
  changeDirection = iChangeDirection;
  pinMode(OutputA, INPUT);
  pinMode(OutputB, INPUT);
  rotationCount = 0;
  rotationDir = 1;
  oldA = -1;
  oldB = -1;
  previousPinChange = 9;
  //void* changeDirection = (*iChangeDirection);
}
--------------------------------------
Part of my main ino file that uses my class:
--------------------------------------
#include "Grayhill61C.h"

void encStep() {

}

void encDir() {

}

Grayhill61C enc = Grayhill61C(9, 10, make_function(encStep), make_function(encDir));
--------------------------------------
Full error message from IDE:
--------------------------------------
sketch/Grayhill61C.cpp: In constructor 'Grayhill61C::Grayhill61C(int, int, function<void()>, function<void()>)':
Grayhill61C.cpp:8:3: error: no matching function for call to 'function<void()>::function()'
   ) {
   ^
In file included from sketch/Grayhill61C.cpp:1:0:
sketch/Grayhill61C.h:19:3: note: candidate: function<R(Args ...)>::function(function<R(Args ...)>::function_type) [with R = void; Args = {}; function<R(Args ...)>::function_type = void (*)()]
   function(function_type f) : function_ptr(f){};
   ^
sketch/Grayhill61C.h:19:3: note:   candidate expects 1 argument, 0 provided
sketch/Grayhill61C.h:13:7: note: candidate: constexpr function<void()>::function(const function<void()>&)
 class function<R(Args...)> {
       ^
sketch/Grayhill61C.h:13:7: note:   candidate expects 1 argument, 0 provided
sketch/Grayhill61C.h:13:7: note: candidate: constexpr function<void()>::function(function<void()>&&)
sketch/Grayhill61C.h:13:7: note:   candidate expects 1 argument, 0 provided
Grayhill61C.cpp:8:3: error: no matching function for call to 'function<void()>::function()'
   ) {
   ^
In file included from sketch/Grayhill61C.cpp:1:0:
sketch/Grayhill61C.h:19:3: note: candidate: function<R(Args ...)>::function(function<R(Args ...)>::function_type) [with R = void; Args = {}; function<R(Args ...)>::function_type = void (*)()]
   function(function_type f) : function_ptr(f){};
   ^
sketch/Grayhill61C.h:19:3: note:   candidate expects 1 argument, 0 provided
sketch/Grayhill61C.h:13:7: note: candidate: constexpr function<void()>::function(const function<void()>&)
 class function<R(Args...)> {
       ^
sketch/Grayhill61C.h:13:7: note:   candidate expects 1 argument, 0 provided
sketch/Grayhill61C.h:13:7: note: candidate: constexpr function<void()>::function(function<void()>&&)
sketch/Grayhill61C.h:13:7: note:   candidate expects 1 argument, 0 provided
exit status 1
no matching function for call to 'function<void()>::function()'
--------------------------------------