template<class X> X & mu(X & x) { return x; }

template<class F, class A1> class bind1
{
private:

    F f_;
    A1 a1_;

public:

    bind1(F const & f, A1 const & a1): f_(f), a1_(a1) {}

    decltype( (*(F*)0)(mu(*(A1*)0)) ) operator()()
    {
        return f_(mu(a1_));
    }
};

template<class F, class A1> bind1<F, A1> bind(F f, A1 a1)
{
    return bind1<F, A1>(f, a1);
}

struct square
{
	template<class T> T operator()(T x) const { return x * x; }
};

#include <iostream>

int main()
{
	std::cout << bind(square(), 5)() << std::endl;
}