clojure.core/while

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Type: macro Added: Clojure 1.0 Examples: 2 Runnable: 1

([test & body])

Repeatedly executes body while test expression is true. Presumes some side-effect will cause test to become false/nil. Returns nil

Examples

by dakrone on 2010-07-31 ▶

;; a var to be used for its side effects (def a (atom 10)) ;; #'user/a (while (pos? @a) (println @a) (swap! a dec)) ;; 10 ;; 9 ;; 8 ;; 7 ;; 6 ;; 5 ;; 4 ;; 3 ;; 2 ;; 1 ;;=> nil

by reborg on 2016-07-30 . May have evaluation errors. ▶

;; calculate the MD5 of a file incrementally: (import 'java.io.File 'javax.xml.bind.DatatypeConverter 'java.security.MessageDigest 'java.security.DigestInputStream) (require '[clojure.java.io :as io]) (defn md5-file [file] (let [sha (MessageDigest/getInstance "MD5")] (with-open [dis (DigestInputStream. (io/input-stream file) sha)] (while (> (.read dis) -1))) (DatatypeConverter/printHexBinary (.digest sha)))) (md5-file (File. "/etc/hosts")) ;; "04F186E74288A10E09DFBF8A88D64A1F33C0E698AAA6B75CDB0AC3ABA87D5644"

See also

• clojure.core/loop (10)
• clojure.core/dotimes (1)
• clojure.core/repeatedly (3)
• clojure.core/swap! (6)
• clojure.core/atom (2)

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