How do I create a function_list<> class to a hold a vector of std::function<>s with the same template syntax?

I wish to have a function_list<> template class that holds a vector of std::function<> values. A key point is that I want to declare my list with the same form I would declare a single std::function<>. e.g.

function_list<void()> functions; // list of std::functions that take and return void

Below is my attempt to implement this. I tried to follow the same syntax used by the std::function<> template in the functional header file of the standard library.

#include <functional>
#include <vector>
#include <iostream>

template<class _R, class... _Args>
class function_list<_R(_Args...)>
{
public:
  std::vector<std::function<_R(_Args...)>> functions;
};

int main()
{
  function_list<void()> fl;
  fl.functions.push_back([]() { std::cout << "Hello, World!" << std::endl; });
  fl.functions.push_back([]() { std::cout << "Goodbye, Cruel World!" << std::endl; });

  for (auto& f : fl.functions)
    f();

  return 0;
}

This doesn't compile and fails with the following errors (clang on OSX 10.14):

test.cpp:6:7: error: explicit specialization of non-template class 'function_list'
class function_list<_R(_Args...)>
      ^            ~~~~~~~~~~~~~~
test.cpp:9:28: error: function cannot return function type 'void ()'
        std::vector<std::function<_R(_Args...)>> functions;
                                  ^
test.cpp:14:24: note: in instantiation of template class 'function_list<void ()>' requested here
        function_list<void()> fl;
                              ^
2 errors generated.

What am I doing wrong? Thanks for your help.