I'm not sure if this is the right location for this type of question, but since I don't see a drools-specific forum and I do see drools posts in this forum, here goes...
I have what I think is a very simple rule to implement, but I can't find a way to do it without "cheating" by using an eval/function. Here's the basic rule in English:
Reject a claim if it contains a treatment that has already been claimed more than 70 times in the same calendar month.
rule
when
Treatment(id=="t1", status=="pending")
Treatment(id=="t1", status=="paid")
Treatment(id=="t1", status=="paid")
then
assert ( new Rejection("reason"));
end