Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!bbn!oberon!randvax!narain
From: narain@randvax.UUCP (Sanjai Narain)
Newsgroups: comp.lang.prolog
Subject: Re: Constraint satisfaction in LOG(F)
Message-ID: <1942@randvax.UUCP>
Date: 9 Apr 89 00:19:11 GMT
References: <1632@kulcs.kulcs.uucp>
Organization: Rand Corp., Santa Monica, Ca.
Lines: 23

Lee, thanks for pointing out that make_list(ans,Z) should be used instead
of reduce(ans,Z).  My point was simply that coroutining can be
accomplished efficiently, invisibly, and in *straight* Prolog.  The
underlying theoretical basis is well worked out in the form of
completeness, computational determinism, confluence and optimality
results.

It is interesting that the NAC compiler can generate coroutining
information automatically.  I would be interested in knowing how general
it is.  Does the user ever have to specify coroutining annotations, or
does the compiler always do the right thing?  Can it handle arbitrary
symbolic generate and test predicates, or did it do a good job because it
knew about +?

As to Bart's message, I never said that coroutining could not be
programmed in Prolog. Of course it can be. My point was that its
programming can greatly obscure the logic of the program. This
does appear to be the case in Bart's program. Yes, it is a lot
faster, but then wouldn't it be even faster in C?

Regards.

Sanjai Narain