sfinae to detect containers: failure for std:array

  c++, sfinae, variadic-templates

I am looking for a way to use SFINAE to implement some function, that must be available only to some containers:
vector, list, array (set is there below only as a test)

Build upon this answer, I tried the code below that uses a traits class that returns true only for the required containers.

As you can see online here, it fails for std::array.

template <typename Container>
struct is_container : std::false_type { };

template <typename... Ts> struct is_container<std::array<Ts... >> : std::true_type { };
template <typename... Ts> struct is_container<std::vector<Ts...>> : std::true_type { };
template <typename... Ts> struct is_container<std::set<Ts...   >> : std::true_type { };
template <typename... Ts> struct is_container<std::list<Ts...  >> : std::true_type { };
template <typename... Ts> struct Dummy{};

int main()
{
    std::cout << "Dummy: " << is_container<Dummy<int>>::value << 'n';
    std::cout << "array: " << is_container<std::array<int,5>>::value << 'n';
    std::cout << "vector:" << is_container<std::vector<int>>::value << 'n';
    std::cout << "set: "   << is_container<std::set<int>>::value << 'n';
    std::cout << "list: "  << is_container<std::list<int>>::value << 'n';
}

What I understand is that this is due to the fact that std::array requires a second template parameter.
I have a low experience with variadic templates, so my question is:

Is there a way to make this approach successful?
Or shall I use another approach described in the linked question?

I’d rather have something pure C++11, but C++14 would be ok too.

Source: Windows Questions C++

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