dictionary-ref now returns a pair or #f

contrib/40.srfi/srfi/17.scm

@@ -17,9 +17,9 @@
     (letrec ((setter
               (lambda (proc)
                 (let ((setter (dictionary-ref (attribute proc) '@@setter)))
-                  (if (undefined? setter)
-                      (error "no setter found")
-                      setter))))
+                  (if setter
+                      (cdr setter)
+                      (error "no setter found")))))
              (set-setter!
               (lambda (proc setter)
                 (dictionary-set! (attribute proc) '@@setter setter))))

docs/libs.rst

@@ -117,7 +117,7 @@ Symbol-to-object hash table.
 
 - **(dictionary-ref dict key)**
 
-  Look up dictionary dict for a value associated with key. If dict has a slot for key `key`, the value stored in the slot is returned. Otherwise `#undefined` is returned.
+  Look up dictionary dict for a value associated with key. If dict has a slot for key `key`, a pair containing the key object and the associated value is returned. Otherwise `#f` is returned.
 
 - **(dictionary-set! dict key obj)**
 

extlib/benz/dict.c

@@ -116,9 +116,9 @@ pic_dict_dictionary_ref(pic_state *pic)
   pic_get_args(pic, "dm", &dict, &key);
 
   if (! pic_dict_has(pic, dict, key)) {
-    return pic_undef_value();
+    return pic_false_value();
   }
-  return pic_dict_ref(pic, dict, key);
+  return pic_cons(pic, pic_obj_value(key), pic_dict_ref(pic, dict, key));
 }
 
 static pic_value