clojure.core/iterate

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Type: function Added: Clojure 1.0 Examples: 4 Runnable: 0

([f x])

Returns a lazy (infinite!) sequence of x, (f x), (f (f x)) etc. f must be free of side-effects

Examples

by nipra on 2010-07-13 . May have evaluation errors. ▶

;; iterate Ad Infinitum starting at 5 using the inc (increment) function (iterate inc 5) (5 6 7 8 9 10 11 12 13 14 15 ... n ... ;; limit results (take 3 (iterate inc 5)) (5 6 7) (take 10 (iterate (partial + 2) 0)) (0 2 4 6 8 10 12 14 16 18) (take 20 (iterate (partial + 2) 0)) (0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38)

by citizen428 on 2010-08-02 . May have evaluation errors. ▶

(def powers-of-two (iterate (partial * 2) 1)) #'user/powers-of-two (nth powers-of-two 10) 1024 (take 10 powers-of-two) (1 2 4 8 16 32 64 128 256 512)

by shockbob on 2011-07-16 . May have evaluation errors. ▶

;; demonstrating the power of iterate ;; to generate the Fibonacci sequence ;; uses +' to promote to BigInt (def fib (map first (iterate (fn [[a b]] [b (+' a b)]) [0 1]))) #'user/fib (take 10 fib) (0 1 1 2 3 5 8 13 21 34)

by reborg on 2018-03-13 . May have evaluation errors. ▶

;; iterate (also range, repeat and cycle) have a reduce ;; fast path. Use with reduce, transduce, eduction etc. (defn pi "Approximate Pi to the 1/n decimal with Leibniz formula" [n] (transduce (comp (map #(/ 4 %)) (take n)) + (iterate #(* ((if (pos? %) + -) % 2) -1) 1.0))) (time (pi 1e8)) "Elapsed time: 9776.924934 msecs" ;; 3.141592643589326

See also

• clojure.core/cycle (2)
• clojure.core/repeatedly (3)
• clojure.core/repeat (2)
• clojure.core/take (3)
• clojure.core/nth (1)
• clojure.core/iteration

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