promote Jason Wolfe's superset?, subset? #338

Signed-off-by: Stuart Halloway <stu@thinkrelevance.com>

src/clj/clojure/set.clj

@@ -139,6 +139,22 @@
                    ret)))
              #{} s))))
 
+(defn subset? 
+  "Is set1 a subset of set2?"
+  {:added "1.2",
+   :tag Boolean}
+  [set1 set2]
+  (and (<= (count set1) (count set2))
+       (every? set2 set1)))
+
+(defn superset? 
+  "Is set1 a superset of set2?"
+  {:added "1.2",
+   :tag Boolean}
+  [set1 set2]
+  (and (>= (count set1) (count set2))
+       (every? set1 set2)))
+
 (comment
 (refer 'set)
 (def xs #{{:a 11 :b 1 :c 1 :d 4}

test/clojure/test_clojure/clojure_set.clj

@@ -179,4 +179,28 @@
 
 (deftest test-map-invert
   (are [x y] (= x y)
-    (set/map-invert {:a "one" :b "two"}) {"one" :a "two" :b}))
+       (set/map-invert {:a "one" :b "two"}) {"one" :a "two" :b}))
+
+(deftest test-subset?
+  (are [sub super] (set/subset? sub super)
+       #{} #{}
+       #{} #{1}
+       #{1} #{1}
+       #{1 2} #{1 2}
+       #{1 2} #{1 2 42})
+  (are [notsub super] (not (set/subset? notsub super))
+       #{1} #{}
+       #{2} #{1}
+       #{1 3} #{1}))
+
+(deftest test-superset?
+  (are [super sub] (set/superset? super sub)
+       #{} #{}
+       #{1} #{}
+       #{1} #{1}
+       #{1 2} #{1 2}
+       #{1 2 42} #{1 2})
+  (are [notsuper sub] (not (set/superset? notsuper sub))
+       #{} #{1}
+       #{2} #{1}
+       #{1} #{1 3}))