Re: for Iteration bug

From: Joachim Schimpf <j.schimpf_at_icparc.ic.ac.uk>
Date: Fri 04 Mar 2005 03:09:45 PM GMT
Message-ID: <42287A39.8010907@icparc.ic.ac.uk>
Mark Wallace wrote:
> In ECLiPSe Version 5.8 #78 (and earlier ECLiPSe releases), the following 
> goal fails to halt:
> ?- ( for(I,1,2), for(J,2,4) do writeln(I-J) )

You mean "fails to fail" :-)


The User Manual sort of says the right thing:

"If several specifiers impose termination conditions, these conditions
must coincide, i.e. specify the same number of iterations."

but the Reference Manuals lies:

"Fails if one of the Goals fails, or if two IterationSpecs specify
a different number of iterations."

I am afraid it would be an inacceptable overhead to resolve this
in the sense of the Reference Manual because we'd have to precisely
compute the 3-way split:

All termination conditions true: stop
All termination conditions false: continue
Otherwise: fail


-- 
  Joachim Schimpf              /             phone: +44 20 7594 8187
  IC-Parc                     /      mailto:J.Schimpf@imperial.ac.uk
  Imperial College London    /    http://www.icparc.ic.ac.uk/eclipse
Received on Fri Mar 04 15:09:46 2005

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