Dictionary reduce, prepare members-base usage.

dictionary.scm

@@ -34,6 +34,7 @@
   dict-keys
   dict-map
   dict-filter
+  dict-reduce
   dictionary-tests!
   )
 
@@ -117,6 +118,16 @@
 		   (cons (car d) r)
 		   r)))))
 
+ ;; Reduce over dictinary, the reducing procedure gets accumulator,
+ ;; key and value as its three arguments.
+ (define (dict-reduce init proc d)
+   (let loop ((d d)
+	      (acc init))
+     (if (null? d)
+	 acc
+	 (loop (cdr d)
+	       (proc acc (caar d) (cdar d))))))
+
  ;; Performs self-tests of the dictionary module.
  (define (dictionary-tests!)
    (run-tests
@@ -144,6 +155,9 @@
 					 '((a . 1)
 					   (b . 2)))
 		'((a . 1)))
+   (test-eq? dict-reduce
+	     (dict-reduce 0 (lambda (a k v) (+ a v)) '((a . 1) (b . 2)))
+	     3)
    ))
 
  )