Generic function using id type

generic_id.m

static int counter = 0;

// ...

id (^retainable_object_)(id(^)(void)) = ^ id (id(^object)(void)) {
    return ^{
        return object();
    };
};

id (^(^retain_object_)(id(^)(void)))(void) = ^ (id(^retainable_object)(void)) {
    id retained_object = retainable_object();
    return ^ id {
        return retained_object;
    };
};

static unsigned long (^(^iterator_)(const unsigned long))(id(^)(void)) = ^ (const unsigned long object_count) {
    typeof(id(^)(void)) retained_objects_ref;
    return ^ (id * retained_objects_t) {
        static typeof(unsigned long(^)(unsigned long)) recursive_iterator_;
        return ^ (id(^object)(void)) {
            return (recursive_iterator_ = ^ unsigned long (unsigned long index) {
                printf("index population count == %lu (object %lu of %lu)\n", index/*((~index + 1UL) & index)*/, [(NSNumber *)(object()) unsignedLongValue], object_count);
                return ((index) >> 1UL) && (recursive_iterator_)((index) >> 1UL);
            })((1UL << object_count) >> 1UL);
        };
    }((id *)&retained_objects_ref);
};

// ....

id (^object_)(void) = ^{
    NSNumber * number = @(++counter);
    return number;
};
    
iterator_(5)(object_);