Re: [eclipse-clp-users] CHR rule remains as delayed goal

From: Kish Shen <kisshen_at_...5...>
Date: Mon, 04 Apr 2011 12:05:08 +0100
Hi Ulrich,

On 04/04/2011 10:25, Ulrich Scholz wrote:
> Hi,
>
> I'm using the library ech as part of a larger application.  Of late, running
> the application leaves a CHR rule as delayed goal:
>
> Delayed goals:
>          types : typeCHR(0, 0, 0, 0, 0, 0, killed)
>
> That's the first time I see a CHR rule as delayed goal and otherwise, the
> application seems to be correct.  Because I try to avoid leaving delayed
> goals (or, e.g., leaving choice points behind) and I want to understand what
> happens, I would like to know where and why this goal delays.
>
> But I have no clue.  Could you point me to some obvious starting points for
> my search?

A CHR constraint that is still in the CHR constraint store at the end of 
the execution is shown as a delayed goal. This is not necessarily 
incorrect. If you don't expect any CHR constraint to be left in the 
store, then you need to look at your CHR code to see why the constraint 
was not removed by your CHR rules. Unfortunately lib(ech) does not 
currently provide much debugging facilities, so that when you trace the 
execution of the CHR code, you see the "raw" ECLiPSe code (generated by 
lib(ech) from transforming your source CHR code), which is not easy to 
follow or map back to your source code.

Cheers,

Kish


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Received on Mon Apr 04 2011 - 11:05:20 CEST

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