Programmation déclarative - Q1AB - 08/2012

(define (myreverse string)
  (letrec
      ((reverse (lambda (string reversed)
                    (if (= (length string) 0)
                        reversed
                        (reverse (cdr string) (cons (car string) reversed))
                        )
                    )
                ))
    (reverse string '())
    )
  )


(define (palindrome string boolean)

      (if boolean
          (append string (myreverse string))
          (append string (cdr (myreverse string)))
          )
  )

(define (palindrome? string)
  (letrec
      ((split (lambda (string1 string2)
                (if (= (length string1) (length string2))
                    (list string1 string2)
                    (if (= (length string1) (+ (length string2) 1))
                        (list (cdr string1) string2)
                        (split (cdr string1) (append string2 (list (car string1))))
                    )
                ))
              ))
    (let
        ((splitted (split string '())))
      (equal? (myreverse (car splitted)) (cadr splitted))
      )
    )
  )