New module accumulators.clj (with example and entry in build.xml)

1 files changed, 58 insertions, 0 deletions

diff --git a/src/clojure/contrib/accumulators/examples.clj b/src/clojure/contrib/accumulators/examples.clj
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+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;
+;; Accumulator application examples
+;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(use 'clojure.contrib.accumulators)
+
+; Vector accumulator: combine is concat, add is conj
+(combine [:a :b] [:c :d] [:x :y])
+(add [:a :b] :c)
+(add-coll empty-vector [:a :b :a])
+
+; List accumulator: combine is concat, add is conj
+(combine '(:a :b) '(:c :d) '(:x :y))
+(add '(:a :b) :c)
+(add-coll empty-list [:a :b :a])
+
+; Set accumulator: combine is union, add is conj
+(combine #{:a :b} #{:c :d} #{:a :d})
+(add #{:a :b} :c)
+(add-coll empty-set [:a :b :a])
+
+; Map accumulator: combine is merge, add is conj
+(combine {:a 1} {:b 2 :c 3} {})
+(add {:a 1} [:b 2])
+(add-coll empty-map [[:a 1] [:b 2] [:a 0]])
+
+; Counter accumulator
+(let [c1 (add-coll empty-counter [:a :b :a])
+      c2 (add-coll empty-counter [:x :y])]
+  (combine c1 c2))
+
+; Counter-with-total accumulator
+(let [c1 (add-coll empty-counter-with-total [:a :b :a])
+      c2 (add-coll empty-counter-with-total [:x :y])]
+  (combine c1 c2))
+
+; Sum accumulator: combine is addition
+(let [s1 (add-coll empty-sum [1 2 3])
+      s2 (add-coll empty-sum [-1 -2 -3])]
+  (combine s1 s2))
+
+; Product accumulator: combine is multiplication
+(let [p1 (add-coll empty-product [2 3])
+      p2 (add-coll empty-product [(/ 1 2)])]
+  (combine p1 p2))
+
+; String accumulator: combine is concatenation
+(combine "a" "b" "c" "def")
+(add "a" (char 44))
+(add-coll empty-string [(char 55) (char 56) (char 57)])
+
+; Accumulator tuples permit to update several accumulators in parallel
+(let [pair (empty-tuple [empty-vector empty-string])]
+  (add-coll pair [[1 "a"] [2 "b"]]))