; COSC 152
; Fall 2005
; Dennis Brylow
;
; Lecture 5 Demo
; Some Scheme functions out of the book.

(define member?
  (lambda (a lst)
    (cond
      ((null? lst) #f)
      (else (or (eq? (car lst) a)
                (member? a (cdr lst))))
      )
    )
  )

(define rember
  (lambda (a lst)
    (cond
      ((null? lst) '())
      (else (if (eq? a (car lst)) 
                (cdr lst)
                (cons (car lst) 
                      (rember a (cdr lst)))))
      )
    )
  )

; Recursion-"star"

(define member*?
  (lambda (a lst)
    (cond
      ((null? lst) #f)
      ((list? (car lst)) (or (member*? a (car lst))
                             (member*? a (cdr lst))))
      (else (or (eq? (car lst) a)
                (member*? a (cdr lst))))
      )
    )
  )

(define rember*
  (lambda (a lst)
    (cond
      ((null? lst) lst)
      ((list? (car lst)) (cons (rember* a (car lst))
                               (rember* a (cdr lst))))
      (else (if (eq? (car lst) a)
                (rember* a (cdr lst))
                (cons (car lst)
                      (rember* a (cdr lst)))))
      )
    )
  )