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Internet Message Format  |  1995-02-09  |  759b
  1. Received: by cheltenham.cs.arizona.edu; Tue, 20 Dec 1994 15:47:42 MST
  2. To: icon-group-l@cs.arizona.edu
  3. Date: 20 Dec 1994 19:29:21 GMT
  4. From: norman@flaubert.bellcore.com (Norman Ramsey)
  5. Message-Id: <3d7bah$q2e@lowell.bellcore.com>
  6. Organization: Bellcore, Morristown NJ
  7. Sender: icon-group-request@cs.arizona.edu
  8. References: <dkuhlmanD0wuqE.I5w@netcom.com>
  9. Subject: Re: Backtracking in Icon
  10. Errors-To: icon-group-errors@cs.arizona.edu
  11.  
  12.  
  13. I use goal-directed evaluation (backtracking) heavily, mostly to
  14. implement predicates of the form ``there exists an X such that P(X).''
  15. I occasionally find other uses.  I wish there were an equally nice way
  16. to write ``forall'' predicates (I usually negate everything in sight
  17. to get an ``exists'' predicate).
  18.