Reimplement and document ldict-reduce.

doc/utils.md

@@ -121,6 +121,17 @@ Returns a new dictionary containing only key/value pairs matching the
 given predicate. The procedure ```pred?``` must accept two arguments -
 the key and the value.
 
+    (ldict-reduce init proc ld)
+
+* ```init``` - initial accumulator value
+* ```proc``` - accumulating procedure
+* ```ld``` - a ldict instance
+
+Performs a reduce operation on the pairs of given dictionary using
+```init``` as initial accumulator. The accumulating procedure must
+accept three arguments: the value accumulated so far, the key and the
+value.
+
 ### IO
 
     (import util-io)

src/util-dict.scm

@@ -193,13 +193,13 @@
 
  ;; Reduce over dictinary, the reducing procedure gets accumulator,
  ;; key and value as its three arguments.
- (define (dict-reduce init proc d)
+ (define (ldict-reduce init proc ld)
-   (let loop ((d d)
+   (let loop ((pairs (ldict-pairs ld))
 	      (acc init))
-     (if (null? d)
+     (if (null? pairs)
 	 acc
-	 (loop (cdr d)
+	 (loop (cdr pairs)
-	       (proc acc (caar d) (cdar d))))))
+	       (proc acc (caar pairs) (cdar pairs))))))
 
  ;; Functional update
  (define (dict-update d k proc . dfls)