Still struggling

[Russ Abbott]

I'm still trying to use Oz like Prolog, and I'm still confused. For example, I was hoping that if X is unbound the following would bind it to elements of Xs.

   proc {IsMember X Xs}
      case Xs of
          Head | Tail then
         choice
           Head = X
         [] {IsMember X Tail}
         end
      end
   end
 

 

If I run

 

      {IsMember Y [1 2 3 4 5]}
      {Browse Y}

 

Ozcar tells me that I get to the 'end' at the bottom of the choice statement with X bound to 1.  At that point the thread turns yellow, saying that it is running.  What is it waiting for?

 

If instead I run

      {Browse {SearchAll proc {$ Y} {IsMember Y [1 2 3 4 5]} end}}

 

the thread turns yellow when it enters SearchAll.  Why don't I get all members of the list as the SearchAll answer?

 

Thanks.

 

-- Russ

--
_____________________________________________
Professor, Computer Science
California State University, Los Angeles
o Check out my blog at http://russabbott.blogspot.com/

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