Transformation by Patterns

Matching and substitution can be combined to transform an input from a pattern-pair: a list of input pattern and output pattern.

(defun transform (pattern-pair input)
  (let (bindings)
    (if (setq bindings
              (match (first pattern-pair) input))
        (sublis bindings (second pattern-pair))) ))

>(transform '( (- ?x (- ?y))  (+ ?x ?y) )
            '(- z (- (* u v))) )

(+ Z (* U V))


>(transform '((- (+ ?x ?y) (+ ?z ?y))
              (- ?x ?z))
            '(- (+ (age tom) (age mary))
                (+ (age bill) (age mary))))

(- (AGE TOM) (AGE BILL))