The two major strands of thought in the design of Oz were concurrency and inference. 'or' (albeit an abstraction programmed from computation spaces these days) combines both in a rather genuine way. I just like to repeat what I said before: Oz is not Prolog, it has been designed to be a successor to Prolog by stressing inference in contrast to blind search. This very idea has boomed over the last two decades in areas such as constraint programming or answer set programming, to just name a few.
Point is: please have a go at writing programs that separate inference from nondeterministic guessing (search). Otherwise you'll be missing out on the major development that underlies the design of Oz (no criticism, just encouragement, please take it that way). I personally, while being very biased and having a different focus on what is reported in CTM, have to admit that CTM does not stress this very fact enough! Christian -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Russ Abbott Sent: Thursday, October 20, 2005 11:51 PM To: Peter Van Roy; Torsten Anders; [EMAIL PROTECTED] Subject: Re: 'or' I'm still confused about 'or' as a statement. What does it mean for it to try to pick between alternatives? Under what conditions will it succeed/fail? I'm guessing that in "trying" it does so in a local copy of the environment to avoid assigning variables. Is that why I saw two different values for a variable--which is not possible without a choice point. Since search engines don't see it, how can it be prompted to resume once it suspends? How is it intended to be used? Or lik 'dis' is it an experimental artifact that is no longer considered part of the language. -- Russ On 10/20/05, Peter Van Roy <[EMAIL PROTECTED]> wrote: ... Note that the 'or' statement does not create a choice point at all. It tries immediately to pick between alternatives and if it can't decide, it will simply suspend. Search engines don't see 'or'. ... _________________________________________________________________________________ mozart-users mailing list [email protected] http://www.mozart-oz.org/mailman/listinfo/mozart-users
