typedef struct Stack<Type, Impl>{
        union Data* stack;
        union Data* data;
        union Data* data1;

        __code whenEmpty(...);
        __code clear(Impl* stack,__code next(...));
        __code push(Impl* stack,Type* data, __code next(...));
        __code pop(Impl* stack, __code next(Type* data, ...));
    /* 途中省略 */
        __code next(...);
} Stack;