eharetea

Deep recursion in Scheme.

Deep recursion with lists in Scheme.

Date Created:Tuesday September 23rd, 2008 10:50 AM
Date Modified:Friday October 03rd, 2008 06:16 PM

(define (rev a)
  (cond
      ((null? a) nil)
      ((list? (car a))
		(append
			(rev (cdr a))
			(list (rev (car a)))
		)
      )
      ((list? a)
            (append
		(cdr a)
		(list (car a))
	    )
      )
      (else a)
  )
)

(define a '((1 2) (3 4)))

(rev a)
((4 3) (2 1))


; DEEP RECURSIVE 

(define (deep-reverse lst)
  (if (atom? lst)
      lst
      (append
            (deep-reverse (cdr lst))
            (list (deep-reverse (car lst))
      )
   )
)

#| 

This counts all elements in all lists and sub-lists

|#

(define (count lst)
  (cond ((null? lst) 0)
        ((not (pair? lst)) 1)
        (else (+ (count (car lst)) (count (cdr lst))))
  )
)

#|
This takes a list of lists of lists... and returns the values within those lists squared
|#

(define (square-list lst)
   (map (lambda (sl)
          (if (pair? sl)
              (square-list sl)
              (* sl sl)
          )
        ) lst
   )
)

Deep Recursion by Dan Lynch
is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License
Based on a work at www.3daet.com
Permissions beyond the scope of this license may be available at http://www.3daet.com