Using aggregations in Cascalog

gistfile1.clj

(def test-tap [["a" "x1" 0 1 0]
                 ["a" "x2" 1 0 1]
                 ["b" "bar" 0 1 0]
                 ["b" "foo" 1 1 0]])

(defaggregatefn dosum
                ([] 0)
                ([state val] (+ state val))
                ([state] [state]))

(defaggregatefn agg-strings
                ([] "")
                ([state val] (str val "|" state))
                ([state] [state]))

(??<- [?id ?s-out ?a-out ?b-out ?c-out]
     (test-tap :> ?id ?s ?a ?b ?c)
     (dosum ?a :> ?a-out)
     (dosum ?b :> ?b-out)
     (dosum ?c :> ?c-out)
     (agg-strings ?s :> ?s-out))
;;=> (["a" "x1|x2|" 1 1 1] ["b" "bar|foo|" 1 2 0])