Enhance hash function to be compatible with Clojure 1.6

project.clj

@@ -7,7 +7,8 @@
   :profiles {:dev {:dependencies [[org.clojure/clojure "1.5.1"]
                                   [criterium "0.4.1"]
                                   [reiddraper/simple-check "0.5.1"]
-                                  [collection-check "0.1.1-SNAPSHOT"]]}}
+                                  [collection-check "0.1.1-SNAPSHOT"]]}
+             :1.6 {:dependencies [[org.clojure/clojure "1.6.0-beta1"]]}}
   :test-selectors {:default (complement :benchmark)
                    :benchmark :benchmark}
   :jvm-opts ^:replace ["-server"])

src/immutable_bitset.clj

@@ -52,6 +52,11 @@
        cnt#
        (p/inc cnt#))))
 
+(defmacro compile-if [test then else]
+  (if (eval test)
+    then
+    else))
+
 (deftype PersistentBitSet
   [^byte log2-chunk-size
    ^int generation
@@ -68,6 +73,12 @@
         (reduce #(p/+ (long %1) (long %2))))))
   (equals [this x] (.equiv this x))
 
+  clojure.lang.IHashEq
+  (hasheq [this]
+    (compile-if (resolve 'clojure.core/hash-unordered-coll)
+      (hash-unordered-coll this)
+      (.hashCode this)))
+
   java.util.Set
   (size [this] (count this))
   (isEmpty [this] (zero? (count this)))