Implement and document predicates for ldict and lset.

src/util-dict-list.scm

@@ -32,6 +32,8 @@
   
   make-ldict
 
+  ldict?
+
   ldict-empty?
   
   ldict-contains?
@@ -76,6 +78,11 @@
 	   (loop (ldict-set ld (caar pairs) (cdar pairs))
 		 (cdr pairs))))))
 
+ ;; Returns true if given value is a ldict
+ (define (ldict? v)
+   (and (pair? v)
+	(eq? (car v) TAG-LDICT)))
+
  ;; Convenience accessors
  (define ldict-meta cadr)
  (define ldict-equality? caadr)