clojure.core/read-line

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

([])

Reads the next line from stream that is the current value of in .

Examples

by gstamp on 2010-08-24 . May have evaluation errors. ▶

(read-line) line to be read ;Type text into console "line to be read"

by kimtg on 2015-03-10 . May have evaluation errors. ▶

;; (flush) is needed to display print values. ;; Otherwise the print value stays buffered until you hit enter. (do (print "What's your name? ") (flush) (read-line)) What's your name? Clojure "Clojure"

by aakoch on 2016-10-05 . May have evaluation errors. ▶

(println "Enter something> ") (def x (read-line)) (println (str "You typed \"" x "\""))

by stathissideris on 2020-08-21 . May have evaluation errors. ▶

;; Example of a tiny menu system. Usage: (menu {:prompt "Which database" :options ["Localhost" "Remote" {:id "o" :text "Other"}]}) ;; Implementation (require '[clojure.string :as str]) (defn menu [{:keys [prompt options]}] (let [options (map (fn [o idx] (if (string? o) {:id (str (inc idx)) :text o} o)) options (range)) valid-options (set (map :id options))] (loop [] (when prompt (println) (println prompt) (println)) (doseq [{:keys [id text]} options] (println (str " [" id "]") text)) (println) (println "or press <enter> to cancel") (let [in (str/trim (read-line))] (cond (= in "") :cancelled (not (valid-options in)) (do (println (format "\n-- Invalid option '%s'!" in)) (recur)) :else (first (filter #(= in (:id %)) options)))))))

Note by bfontaine

Be aware that read-line uses Java’s BufferedReader’s .readLine method that itself uses an internal buffer of either 4k or 8k. That causes (read-line) to return a truncated string if you try to read a large line.

See also

• clojure.core/flush

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