I would have done something like that:
(defrule sum
?f1 <- (purchase ?s1)
?f2 <- (purchase ?s2)
(test (neq ?f1 ?f2))
=>
(retract ?f1)
(retract ?f2)
(assert (purchase (+ ?s1 ?s2)))
)
Works at least with CLIPS but I suppose with Jess as well. How does that
compare performance-wise?
(Of course, your initial facts are gone afterwards - if you want to keep
them, it gets a little more difficult).
tge
[EMAIL PROTECTED] wrote:
>
> The most efficient way to do it would be to use a defquery to find all
> the PURCHASE facts, then iterate over the query result directly and
> add them up. You could define a deffunction to do this.
>
> I think John Goalby wrote:
> > I would like to be able to have the following facts...
> >
> > (assert (PURCHASE 100))
> > (assert (PURCHASE 150))
> > (assert (PURCHASE 70))
> >
> > and then be able to have a rule that would give me the
> > sum of these purchases. Is that possible?
> >
> > Thanks
> >
> > John.
>
--
Thomas Gentsch
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