None versus MISSING sentinel -- request for design feedback

[Gregory Ewing]

Ethan Furman wrote:
> some 
> of the return values (Logical, Date, DateTime, and probably Character) 
> will have their own dedicated singletons (Null, NullDate, NullDateTime, 
> NullChar -- which will all compare equal to None)

That doesn't seem like a good idea to me. It's common practice
to use 'is' rather than '==' when comparing things to None.

Why do you want to use special null values for these types?

-- 
Greg