[Mulgara-dev] Re: [Mulgara-general] Removing exclude.

[Paul Gearon]

On Apr 12, 2007, at 10:58 PM, Andrae Muys wrote:

>
> My current focus is on the Non-union compatible disjunction bug.   
> As a part of this I am back in TuplesOperations.project() and  
> friends, where there is some ugliness resulting from the current  
> implementation of exclude.  I'm not going to get sidetracked on a  
> cleanup job, but it does remind me that we never did reach an  
> agreement on the future of exclude.
>
> As I recall the conversation we hadn't yet found anyone who  
> actually uses it - and of those who have tried to, no-one has  
> managed to actually use it correctly.  It was introduced to provide  
> a limited form of negation, and one that interacts poorly with the  
> open-world assumption.  We also now have minus, which is well  
> defined, corresponds closely to our intuitive understanding of the  
> operation, and is (I am told) what was actually required.
>
> If my memory is correct we should probably at least deprecate, if  
> not remove exclude entirely from mulgara.
>
> Do we agree that exclude should be removed?

Well *I* agree anyway.  As you say, it doesn't do what anyone thinks  
it does.

> If it should be removed, when should this occur?

Yesterday.

Paul