big perf boost to hard0 sudoku by implementing Object equals for Fini…

…teDomain

src/main/clojure/clojure/core/logic.clj

@@ -293,7 +293,7 @@
 
 (declare domain sorted-set->domain
          difference* intersection* disjoint?*
-         unify-with-domain*)
+         unify-with-domain* finite-domain?)
 
 ;; FiniteDomain
 ;; -----
@@ -306,6 +306,13 @@
 ;; max - the maximum value, an optimization
 
 (deftype FiniteDomain [s min max]
+  Object
+  (equals [this that]
+    (if (finite-domain? that)
+      (if (= (member-count this) (member-count that))
+        (= s (:s that))
+        false)
+      false))
   clojure.lang.ILookup
   (valAt [this k]
     (.valAt this k nil))
@@ -366,6 +373,9 @@
   IIntervals
   (intervals [_] (seq s)))
 
+(defn finite-domain? [x]
+  (instance? FiniteDomain x))
+
 (defn sorted-set->domain [s]
   (let [c (count s)]
     (cond

src/main/clojure/clojure/core/logic/bench.clj

@@ -724,7 +724,7 @@
 
   (dotimes [_ 5]
     (time
-     (dotimes [_ 10]
+     (dotimes [_ 1]
        (sudokufd hard0))))
 
   ;; from GeCode test suite