(load "chez-init.ss")    ; Section 04

(define read-flatten-print
  (lambda ()
    (display "enter slist to flatten: ")
    (let ([slist (read)])
      (unless (eq? slist 'exit)
	(flatten-cps slist (rfp-k))))))

(define-datatype kontinuation kontinuation?
  [rfp-k]
  [append-k (first symbol?) (k kontinuation?)]
  [flatten-cdr-k (ls list?) (k  kontinuation?)]
  [flatten-car-k (flattened-cdr list?) (k kontinuation?)])

(define (apply-k k v)
  (cases kontinuation k
    [rfp-k ()
       (pretty-print v)
       (read-flatten-print)]
    [append-k(first k)
       (apply-k k (cons first v))]
    [flatten-cdr-k (ls k)
	(if (list? (car ls))
	    (flatten-cps (car ls) (flatten-car-k v k))
	    (apply-k k (cons (car ls) v)))]
    [flatten-car-k (flattened-cdr k)
	    (append-cps v flattened-cdr k)]))
	     
(define flatten-cps
  (lambda (ls k)
    (if (null? ls)
	(apply-k k ls)
	(flatten-cps (cdr ls) (flatten-cdr-k ls k)))))

(define append-cps 
  (lambda (l1 l2 k)
    (if (null? l1)
	(apply-k k l2)
	(append-cps (cdr l1) l2 (append-k (car l1) k)))))