newlispfanclub.alh.net

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(query '(einstein minor))

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(set 'facts '(
    (socrates philosopher)
    (socrates greek)
    (socrates human)
    (einstein german)
    (einstein (studied physics))
    (einstein human)
    (einstein (age 50))
))

(set 'rules '(
    ((X mortal) <- (X human))
    ((X (knows physics)) <- (X physicist))
    ((X physicist) <- (X (studied physics)))
    ((X minor)  <-   ; what should go here if i need check age is less than 18?
))


(define (query trm)
    (or  (if (find trm facts) true) (catch (prove-rule trm))))

(define (prove-rule trm)
    (dolist (r rules)
        (if (list? (set 'e (unify trm (first r))))
            (if (query (expand (last r) e))
                (throw true))))
    nil
)

#> (query '(socrates human))

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(age 50)