CLIPS compare 2 dates - clips

Question

I'm trying to compare 2 dates to see if one person is older than 25 years old. I tried to bind a variable to the subtraction of the current date and his birthday, and then compare the variable to 25:
(deftemplate data
(multislot current_date (type INTEGER))
)
(deffacts today
(data (current_date 12 4 2018))
)
(deftemplate driver
(multislot name)
(multislot dateBorn)
)
(deffacts drivers
(driver (name Daniel Silva)(dateBorn 3 4 1985))
(driver (name Carlos Santos)(dateBorn 3 4 2000))
)
(defrule cantDrive
(driver(dateBorn $? ?age))
(data (current_date $? ?date))
(bind ?data (- ?age ?date))
(test(< ?data 25))
=>
(printout t "He is younger than 25" crlf)
)
The above code doesn’t run, and I don’t understand why. Is there any operation that is incorrect? Is there any way to compare two dates? For example, I was born in 26/06/1997 and if I need to be at least 25 to rent a car, how do I confirm that?
I can set the current date.

Answer 1

CLIPS (6.31 2/3/18)
CLIPS>
(deffunction current-date ()
(bind ?lt (local-time))
(format nil "%04d-%02d-%02d" (nth$ 1 ?lt) (nth$ 2 ?lt) (nth$ 3 ?lt)))
CLIPS>
(deffunction is-leap-year (?year)
(if (= (mod ?year 400) 0) then (return TRUE))
(if (= (mod ?year 100) 0) then (return FALSE))
(if (= (mod ?year 4) 0) then (return TRUE))
(return FALSE))
CLIPS>
(defglobal ?*days-before-month* = (create$ 0 31 59 90 120 151 181 212 243 273 304 334))
CLIPS> (defglobal ?*days-before-month-leap-year* = (create$ 0 31 60 91 121 152 182 213 244 274 305 335))
CLIPS>
(deffunction days-from-year-begin (?date)
(bind ?year (string-to-field (sub-string 1 4 ?date)))
(bind ?month (string-to-field (sub-string 6 7 ?date)))
(bind ?day (string-to-field (sub-string 9 10 ?date)))
(if (is-leap-year ?year)
then
(return (+ (nth$ ?month ?*days-before-month-leap-year*) ?day))
else
(return (+ (nth$ ?month ?*days-before-month*) ?day))))
CLIPS>
(deffunction days-until-year-end (?date)
(bind ?year (string-to-field (sub-string 1 4 ?date)))
(bind ?month (string-to-field (sub-string 6 7 ?date)))
(bind ?day (string-to-field (sub-string 9 10 ?date)))
(if (is-leap-year ?year)
then
(return (- 366 (+ (nth$ ?month ?*days-before-month-leap-year*) ?day)))
else
(return (- 365 (+ (nth$ ?month ?*days-before-month*) ?day)))))
CLIPS>
(deffunction date-days-diff (?date1 ?date2)
(bind ?year1 (string-to-field (sub-string 1 4 ?date1)))
(bind ?year2 (string-to-field (sub-string 1 4 ?date2)))
(if (= ?year1 ?year2)
then
(return (- (days-from-year-begin ?date1) (days-from-year-begin ?date2))))
(if (> ?year1 ?year2)
then
(bind ?negate FALSE)
else
(bind ?negate TRUE)
(bind ?temp ?date1)
(bind ?date1 ?date2)
(bind ?date2 ?temp)
(bind ?temp ?year1)
(bind ?year1 ?year2)
(bind ?year2 ?temp))
(bind ?day-count (+ (days-until-year-end ?date2) (days-from-year-begin ?date1)))
(loop-for-count (?year (+ ?year2 1) (- ?year1 1)) do
(if (is-leap-year ?year)
then (bind ?day-count (+ ?day-count 366))
else (bind ?day-count (+ ?day-count 365))))
(if ?negate
then
(return (- 0 ?day-count))
else
(return ?day-count)))
CLIPS>
(deffunction date-years-diff (?date1 ?date2)
(bind ?year1 (string-to-field (sub-string 1 4 ?date1)))
(bind ?year2 (string-to-field (sub-string 1 4 ?date2)))
(if (= ?year1 ?year2)
then
(return 0))
(if (> ?year1 ?year2)
then
(bind ?negate FALSE)
else
(bind ?negate TRUE)
(bind ?temp ?date1)
(bind ?date1 ?date2)
(bind ?date2 ?temp))
(bind ?year1 (string-to-field (sub-string 1 4 ?date1)))
(bind ?year2 (string-to-field (sub-string 1 4 ?date2)))
(bind ?month1 (string-to-field (sub-string 6 7 ?date1)))
(bind ?month2 (string-to-field (sub-string 6 7 ?date2)))
(bind ?day1 (string-to-field (sub-string 9 10 ?date1)))
(bind ?day2 (string-to-field (sub-string 9 10 ?date2)))
(bind ?years (- ?year1 ?year2))
(if (= ?month1 ?month2)
then
(if (< ?day1 ?day2)
then
(bind ?years (- ?years 1)))
else
(if (< ?month1 ?month2)
then
(bind ?years (- ?years 1))))
(if ?negate
then (return (- 0 ?years))
else (return ?years)))
CLIPS>
(deftemplate driver
(slot name)
(slot dateBorn))
CLIPS>
(deffacts drivers
(driver (name "Daniel Silva") (dateBorn "1985-03-04"))
(driver (name "Carlos Santos") (dateBorn "2000-03-04")))
CLIPS>
(defrule cantDrive
(driver (name ?name) (dateBorn ?born))
(test (< (date-years-diff (current-date) ?born) 25))
=>
(printout t ?name " is younger than 25" crlf))
CLIPS> (reset)
CLIPS> (run)
Carlos Santos is younger than 25
CLIPS>