maybe.cpp

#include <iostream>
using namespace std;

template<class X> using Maybe = std::unique_ptr<X>;

template<class X> Maybe<X> Just(const X& x)
{
    return Maybe<X>( new X(x) );
}

template<class X> Maybe<X> Nothing()
{
    return Maybe<X>(nullptr);
}

template<class X> const X& fromJust(const Maybe<X>& m)
{
    return *m;
}

int main(void)
{
    auto x = Just<bool>(false);

    if(x != Nothing<bool>())
        std::cout << fromJust(x) << std::endl;
    return 0;
}