Jess is a rule language whose basic mechanism is pattern matching, which
binds pattern variables to constants. If you have a fact of the form
(person (name Fred) (age 22))
then you can issue a query of the form
(person (name ?name) (age ?age))
and it will bind ?name to Fred and ?age to 22 (if
Could you please show me the guidance???
I'm trying to modify the ?new fact for tallying his expenses, something like
this in Java code:
double expense = 1000;
expense = expense + 2000; // trying to get the previous amount add up with
the current amount
(deftemplate (slot name) (slot age)
Hello,
I agree with John, you should take a course through the tutorials first,
it would help you a lot.
Now, in your question, it seems that you need to access the slot of a
specific fact that you've just bound.
In this case, you can access slots directly with a . (like an object
field):
First of all, you might tell us why you don't want to use modify? I
can't see any good reason for that.
I think a perfectly valid notation in your case would be :
(modify ?new (expense (+ 2000 ?new.expense)))
Now if you're not familiar with LISP-like notation, you have a lot of
guidance here:
