* src/main/clojure/clojure/core/match.clj: add defpred, add validatio…

…n on :when, fix related tests

src/main/clojure/clojure/core/match.clj

@@ -1321,6 +1321,14 @@
 ;; predicates are desired, use guard patterns.
 ;;
 
+(def preds (atom {}))
+
+(defmacro defpred
+  ([name]
+     (swap! preds assoc name name))
+  ([name f]
+     (swap! preds assoc name f)))
+
 (declare predicate-pattern?)
 
 (deftype PredicatePattern [p gs _meta]
@@ -1529,8 +1537,11 @@
   [[p _ sym]] (with-meta (emit-pattern p) {:as sym}))
 
 (defmethod emit-pattern-for-syntax [Object :when]
-  [[p _ gs]] (let [gs (if (not (vector? gs)) [gs] gs)]
-              (predicate-pattern (emit-pattern p) (set gs))))
+  [[p _ gs]]
+  (let [gs (if (not (vector? gs)) [gs] gs)]
+    (assert (every? symbol? gs) (str "Invalid predicate expression " gs))
+    (assert (every? #(contains? @preds %) gs) (str "Unknown predicate in " gs))
+    (predicate-pattern (emit-pattern p) (set gs))))
 
 (defmethod emit-pattern-for-syntax [Object :guard]
   [[p _ gs]] (let [gs (if (not (vector? gs)) [gs] gs)]

src/test/clojure/clojure/core/match/test/core.clj

@@ -161,6 +161,10 @@
 (defn div3? [n]
     (= (mod n 3) 0))
 
+(defpred even?)
+(defpred odd?)
+(defpred div3?)
+
 (deftest guard-pattern-match-1
   (is (= (let [y '(2 3 4 5)]
            (match [y]
@@ -189,9 +193,9 @@
 
 (deftest guard-pattern-match-4
   (is (= (match [1 2]
-                [(a :guard #(odd? %)) (b :when #(odd? %))] :a1
+           [(a :guard #(odd? %)) (b :when odd?)] :a1
                 [(a :guard #(odd? %)) _] :a2
-                [_ (b :when #(even? %))] :a3
+                [_ (b :when even?)] :a3
                 :else :a4)
          :a2)))
 
@@ -239,7 +243,7 @@
                 op (first e)
                 op? #(= % op)]
             (match [e]
-                   [([p :when op? x ([p2 :when op? y z] :seq)] :seq)] (list p x y z)))
+                   [([p :guard op? x ([p2 :guard op? y z] :seq)] :seq)] (list p x y z)))
           '(+ 1 2 3))))
 
 (deftest quoted-symbol