Hi,
both Luis and Denys are right (how Salomonian of me ;-) ). Oz used to employ
the top-commit rule (allow the disjunction to reduce with an entailed
clause, provided its body is skip). However the current system does not
implement it (their use seemed to be limited at that time).
I begin to see that there is new and revived interest in combinators. Also
it appears to me that we are lacking documentation of their semantics. Also,
there have been questions raised regarding their semantics. I can only
reassure that programming combinators is reasonably easy and getting at your
favourite disjunction is simple -- this is the true advantage of spaces.
So don't feel confined to the combinators that are there, build your own. If
you are then convinced make a proposal of inclusion into the system.
With other words: design, hack, discuss and contribute!
Christian
-- Christian Schulte, http://www.ps.uni-sb.de/~schulte/----- Original Message ----- From: "Luis Quesada" <luque@info.ucl.ac.be> Newsgroups: mozart-oz.users To: <users@mozart-oz.org> Sent: Thursday, September 20, 2001 9:39 PM Subject: Re: "or" statement
> Denys Duchier wrote: > > > > 1. The or commits to the entailed option, which would not add any new > > > information to the store. > > > 2. The or keeps suspended for ever , which would not add anything new > > > neither. > > > > neither of your suggestions is faithful to the semantics. > > > > Perhaps you did not read my last message. I am just considering or statements > where the bodies are skip. > > or > G1 then skip > [] > G2 then skip > [] > . > . > [] > Gn then skip > end > > Having that in mind, I just see two possibilities when one of the guards is > entailed: > > 1. All the other guards fail and the space of the entailed guard is merged with > its parent. > 2. There is not commitment since there is at least one other sibling space that > keep unfailed. > > I don't see any other option, do you? > > Actually, I already found the answer to my question in Christian's thesis. In > section 11.4 of its thesis he gives the semantics of the disjunction. Point 4 of > his definition says: > > "If an alternative is entailed, reduce by discarding all alternatives" > > I certainly agree with him :-) > > Luis > > -- > Catholic University of Louvain > Department of Computing Science and Engineering > Place Sainte Barbe, 2 > B-1348 Louvain-la-Neuve, Belgium > Phone: (++32) (10) 47 90 13 > Fax: (++32) (10) 45 03 45 > E-mail: luque@info.ucl.ac.be > > > > - > Please send submissions to users@mozart-oz.org > and administriva mail to users-request@mozart-oz.org. > The Mozart Oz web site is at http://www.mozart-oz.org/. >
- Please send submissions to users@mozart-oz.org and administriva mail to users-request@mozart-oz.org. The Mozart Oz web site is at http://www.mozart-oz.org/.