(use srfi-1)
(use srfi-13)

(define (empty k)
	'no-such-entry)

(define (add-entry kv f)
	(let ((k (car kv))
		  (v (cadr kv)))
	(lambda (kp) 
		(if (equal? kp k) v
			(f kp)))))

(define flist (fold-right add-entry empty (list '("bing" 1) '("bar" 2) '("foo" 3))))

(print (flist "bar"))
(print (flist "unknown key"))



(define (add-tree-entry kv f g)
	(let ((k (car kv))
		  (v (cadr kv)))
	(lambda (kp)
		(cond ((equal? kp k) v)
			  ((string< kp k) (f kp))
			  ((string> kp k) (g kp))))))

(define ftree (add-tree-entry '("bar" 2) 
	(add-tree-entry '("bab" 1) empty empty) 
	(add-tree-entry '("foo" 0) (add-tree-entry '("ddd" 1234) empty empty)
							   (add-tree-entry '("zoing" 4) empty empty))))

(print (ftree "ddd"))
(print (ftree "zoing"))
(print (ftree "nonsuch"))