5 Examples top

• link | changes

  ;looping is recursive in Clojure, the loop construct is a hack so that something like tail-recursive-optimization works in clojure.
  user=> (defn my-re-seq [re string]
           "Something like re-seq"
           (let [matcher (re-matcher re string)]
  
             (loop [match (re-find matcher) ;loop starts with 2 set arguments
                    result []]
               (if-not match
                 result
                 (recur (re-find matcher)    ;loop with 2 new arguments
                        (conj result match))))))
  
  #'user/my-re-seq
  
  user=> (my-re-seq #"\d" "0123456789")
  ["0" "1" "2" "3" "4" "5" "6" "7" "8" "9"]
  
  

  ;looping is recursive in Clojure, the loop construct is a hack so that something like tail-recursive-optimization works in clojure. user=> (defn my-re-seq [re string] "Something like re-seq" (let [matcher (re-matcher re string)] (loop [match (re-find matcher) ;loop starts with 2 set arguments result []] (if-not match result (recur (re-find matcher) ;loop with 2 new arguments (conj result match)))))) #'user/my-re-seq user=> (my-re-seq #"\d" "0123456789") ["0" "1" "2" "3" "4" "5" "6" "7" "8" "9"]
• link | changes

  ;; Read decoded MP3 data in loop (requires mp3plugin.jar on class path)
  ;; http://java.sun.com/javase/technologies/desktop/media/jmf/mp3/download.html 
  
  (import '(javax.sound.sampled AudioSystem AudioFormat$Encoding))
  
  (let [mp3-file (java.io.File. "tryout.mp3")
        audio-in (AudioSystem/getAudioInputStream mp3-file)
        audio-decoded-in (AudioSystem/getAudioInputStream AudioFormat$Encoding/PCM_SIGNED audio-in)
        buffer (make-array Byte/TYPE 1024)]
    (loop []
      (let [size (.read audio-decoded-in buffer)]
        (when (> size 0)
          ;do something with PCM data
  	(recur)))))
  

  ;; Read decoded MP3 data in loop (requires mp3plugin.jar on class path) ;; http://java.sun.com/javase/technologies/desktop/media/jmf/mp3/download.html (import '(javax.sound.sampled AudioSystem AudioFormat$Encoding)) (let [mp3-file (java.io.File. "tryout.mp3") audio-in (AudioSystem/getAudioInputStream mp3-file) audio-decoded-in (AudioSystem/getAudioInputStream AudioFormat$Encoding/PCM_SIGNED audio-in) buffer (make-array Byte/TYPE 1024)] (loop [] (let [size (.read audio-decoded-in buffer)] (when (> size 0) ;do something with PCM data (recur)))))
• link | changes

  (loop [x 10]
    (when (> x 1)
      (println x)
      (recur (- x 2))))

  (loop [x 10] (when (> x 1) (println x) (recur (- x 2))))
• link | changes

  (defn find-needle [needle haystack]
    ;loop binds initial values once,
    ;then binds values from each recursion call
    (loop [needle needle
           maybe-here haystack
           not-here '()]
  
      (let [needle? (first maybe-here)]
  
        ;test for return or recur
        (if (or (= (str needle?) (str needle))
                (empty? maybe-here))
  
          ;return results
          [needle? maybe-here not-here]
  
          ;recur calls loop with new values
          (recur needle
                 (rest maybe-here)
                 (concat not-here (list (first maybe-here))))))))
  
  user=>(find-needle "|" "hay|stack")
  [\| (\| \s \t \a \c \k) (\h \a \y)]

  (defn find-needle [needle haystack] ;loop binds initial values once, ;then binds values from each recursion call (loop [needle needle maybe-here haystack not-here '()] (let [needle? (first maybe-here)] ;test for return or recur (if (or (= (str needle?) (str needle)) (empty? maybe-here)) ;return results [needle? maybe-here not-here] ;recur calls loop with new values (recur needle (rest maybe-here) (concat not-here (list (first maybe-here)))))))) user=>(find-needle "|" "hay|stack") [\| (\| \s \t \a \c \k) (\h \a \y)]
• link | changes

  ; makes a simple template function that can be used in mustache way: http://mustache.github.com/
  (defn template [tpl env]
    (loop [tpl tpl
           env env]
      (cond (empty? env)
            tpl
            :else
            (let [[key value] (first env)]
              (recur (try (clojure.string/replace tpl 
                                                  (re-pattern (str "\\{\\{" (name key) "\\}\\}")) 
                                                  value)
                          (catch Exception e tpl)) 
                     (rest env))))))

  ; makes a simple template function that can be used in mustache way: http://mustache.github.com/ (defn template [tpl env] (loop [tpl tpl env env] (cond (empty? env) tpl :else (let [[key value] (first env)] (recur (try (clojure.string/replace tpl (re-pattern (str "\\{\\{" (name key) "\\}\\}")) value) (catch Exception e tpl)) (rest env))))))