Igor Stasenko ha scritto:

> What do you think about supporting Sets to contain nils in general,
> and about methods how to achieve that?
> 

Messing in such a way with a standard collection class is definetively 
wrong. What you could do is create another class that implements all 
Set's protocols. In such a class I'd use the instance itself as a 
placeholder to put in the empty slots.

	Giovanni