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zehnpaard/treductions.clj

Last active September 20, 2016 10:10
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Transducing Reductions?
Raw
treductions.clj
(defn treductions [f]
(fn [xf]
(let [last-val (volatile! ::none)]
(fn
([] (xf))
([result] (xf result))
([result input]
(if (= ::none @last-val)
(vreset! last-val input)
(vreset! last-val (f @last-val input)))
(xf result @last-val))))))
;;usage
(sequence (treductions +) (range 10))
;; output : (0 1 3 6 ...)
(sequence (treductions conj) (concat [[]] (range 10)))
;; output : ([] [0] [0 1] [0 1 2]...)
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