Yes, I think the missing "$" was the issue that was preventing this
working. Will reformulate and try (should work).
Thx.
On Feb 20, 2008, at 3:28 AM, Wolfgang Laun wrote:
I would not use this rule provided I understood the problem
correctly as:
"Find all facts foo where the length of foo.my-list equals the value
of slot foo.desired."
The proposed solution does not compare a length with foo.desired,
and binding of a multislot vaue should use a variable starting with
$?.
I think the solution should be written as:
(deftemplate foo (multislot my-list)(slot desired (default 0)))
(defrule lok
?mf <- (foo (my-list $?list)(desired ?len &:(= (length$ $?list) ?
len)))
=>
(printout t ?mf " list " $?list " length " ?l crlf)
)
(deffacts facts
(foo )
(foo (my-list x y)(desired 2))
(foo (my-list a b c)(desired 2))
)
(reset)
(facts)
(run)
kr
Wolfgang
On 2/19/08, Peter Lin <[EMAIL PROTECTED]> wrote:
I believe you need to use
(length$ <multifield-expression>)
and then do a test to compare the two lengths. so the rule might
look like this
(defrule myrule
(foo
(my-list ?list1)
)
(foo
(my-list ?list2)
)
(test (eq (length$ ?list1) (length$ ?list2) ) )
=>
(printout t "the lists have the same length)
)
that's how I've done it in the past. there might be an easier way.
On Feb 19, 2008 4:04 PM, Hal Hildebrand <[EMAIL PROTECTED]>
wrote:
I've been struggling with trying to formulate a LHS which tries to
match the length of one of the fact's multislots with another slot.
For example:
(deftemplate foo (multislot my-list) (slot desired))
I've tried the following:
(foo (my-list ?my-list) (desired = (length$ ?my-list))
(foo { desired == (length$ my-list) } )
(foo (my-list ?my-list { desired == (length$ ?my-list) } )
And even though desired is 0 and the length of the list is 0, the rule
simply won't fire. Obviously, I'm missing something....
--------------------------------------------------------------------
To unsubscribe, send the words 'unsubscribe jess-users
[EMAIL PROTECTED]'
in the BODY of a message to [EMAIL PROTECTED], NOT to the list
(use your own address!) List problems? Notify [EMAIL PROTECTED]
.
--------------------------------------------------------------------
