[m-rev.] for review: negation in trace goals conditions

[Julien Fischer]

On Wed, 21 Feb 2007, Ondrej Bojar wrote:

> Julien Fischer wrote:
>> I wasn't suggesting that you implement it; I was just wondering if
>> the addition of `not' to trace goal conditions was just bandaid solution to 
>> the problem of the conditions not being flexible enough.
>
> To be generic enough, you'd need:
>
>  trace [runtime(mytest)] mygoal,
>
> or
>
>  trace [runtime(test(mytest))] mygoal,
>
> where
>
> :- pred mytest(bool::out, io::di, io::uo) is det.

Where is mytest getting its I/O state from?

> ...which is probably also quite simple to hack, but I do not know enough 
> about  generating predicate calls.

You can already do something equivalent to the above.

 	trace [io(!IO)] (
 		mytest(RunGoal, !IO),
 		(
 			RunGoal = yes,
 			mygoal,
 		;
 			RunGoal = no
 		)
 	).

Julien.
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