Nullable types

[waneck]

We need to think how to generate Nullable types efficiently

My take would be that for every value type there is, we generate something like:

struct Null_int {
    bool hasValue;
    int value;
}

This way Null<Int> is nothing but this struct; Still, we need to think how to interact with type parameters - in special returning values from type parameters

[Simn]

Any more thoughts on this?