[m-dev.] proposal for promise_pure scope warning

[Julien Fischer]

On Tue, 15 Apr 2008, Ian MacLarty wrote:

>
> ( promise_pure ( impure p ) ->
>    true
> ;
>    true
> )
>
> The same applies to the case where there is output, but the output is
> not used.
>
>> (Which is the "bug" I assume you are trying to address here)
>>
>
> That is a symptom, but the underlying problem is that purity is being
> promised away in the wrong spot.  A goal like:
>
>    promise_pure ( impure p )
>
> just makes no sense (regardless of the determinism), because either the
> goal should be impure, or p itself should be pure.

The G12 FD solver uses constructs like the above extensively (which
is one reason I don't want any warning to be enabled by default).

Julien.
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