Null references (oh no, not again!)

[Walter Bright]

Andrei Alexandrescu wrote:
> And there is no reference type with two subtypes. It's one type in the 
> language and one in the library. Maybe-null (the library) is a supertype 
> of non-null (the default).

I don't know how it cannot wind up being two types. One nullable, the 
other not. Whether it is a library type or language type, there are 
still two versions.