;with apply-continuation starting-code
(load "chez-init.ss")

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

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


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



(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)))))