clojure.core/completing

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Type: function Added: Clojure 1.7 Examples: 3 Runnable: 3

([f] [f cf])

Takes a reducing function f of 2 args and returns a fn suitable for transduce by adding an arity-1 signature that calls cf (default - identity) on the result argument.

Examples

by reborg on 2017-11-01 ▶

;; Fix apparently inconsistent behaviour of "-" (minus) with transduce: (transduce (map inc) - 0 (range 10)) ;; 55 (transduce (map inc) (completing -) 0 (range 10)) ;; -55

by reborg on 2017-11-17 ▶

;; the reducing fn arity-1 executes the last transformation in transduce. ;; completing defaults to "identity" but you can change it. ;; Use this fact for example with transients and go back to persistent once done. (require '[clojure.string :refer [lower-case]]) (transduce (comp (remove nil?) (map lower-case)) (completing #(assoc! %1 %2 (inc (get %1 %2 0))) persistent!) (transient {}) ["hi" "ho" "Hello" "hoi" "Hi" "Ha" "ha" "hello"]) ;; {"hi" 2, "ho" 1, "hello" 2, "hoi" 1, "ha" 2}

by naxels on 2022-12-07 ▶

;; Example calculating the average from ;; https://aphyr.com/posts/360-loopr-a-loop-reduction-macro-for-clojure#comment-3800 (transduce (map inc) (completing (fn [[sum cnt] x] [(+ sum x) (inc cnt)]) (fn [[sum cnt]] (/ sum cnt))) [0 0] (range 7)) ;; 4

See also

• clojure.core/transduce (5)

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