Implement rembero2 to resolve discrepancy between book and clojure.logic

rebcabin · rebcabin · commit ee4ae2e5b17a · 2013-07-16T06:29:22.000-07:00
diff --git a/mini-kanren/src/mini_kanren/utils.clj b/mini-kanren/src/mini_kanren/utils.clj
@@ -167,15 +167,15 @@
               (memo x d out)))))
 
 ;;; Frame 4-24
-#_(defn rembero
+(defn rembero2
   "Succeeds when out equals l with the first occurrence of x removed."
   [x l out]
   (conde
    ((emptyo l) (== () out))
    ((eq-caro l x) (resto l out))
    (s# (fresh [a d res]
               (resto l d)
-              (rembero x d res)
+              (rembero2 x d res)
               (firsto l a)
               (conso a res out)
               ))))
diff --git a/mini-kanren/test/mini_kanren/core_test.clj b/mini-kanren/test/mini_kanren/core_test.clj
@@ -721,4 +721,14 @@
             (fresh [y z]
                    (rembero y (list y 'd z 'e) (list y 'd 'e))
                    (== (list y z) r)))))
+
+  ;; Resolve this mystery by implementing our own rembero, called
+  ;; rembero2, in the file utils.clj, according to the guidelines in
+  ;; Frame 4-24. TODO: examine the implementation of "rember" in
+  ;; clojure.core/logic. 
+  (test/is (=
+             '([(d d) d d] [(d d) d d] [(_0 _0) _0 _0] [(e e) e e]
+               ) (run* [r y z]
+                       (rembero2 y (list y 'd z 'e) (list y 'd 'e))
+                       (== (list y z) r))))
 )
