extend_core.clj

;;Code courtesy of Chas Emerick
(let [slurp* (fn [f]
	       (with-open [#^java.io.BufferedReader r (java.io.BufferedReader. f)]
		 (let [sb (StringBuilder.)]
		   (loop [c (.read r)]
		     (if (neg? c)
		       (str sb)
		       (do (.append sb (char c))
			   (recur (.read r))))))))]
  (defn silent-read
    [s]
    (try
     (let [r (-> s java.io.StringReader. java.io.PushbackReader.)]
       [(read r) (slurp* r)])
     (catch Exception e))))

(defn interpolate-worker
  ([s atom?]
    (lazy-seq
      (if-let [[form rest] (silent-read (subs s (if atom? 2 1)))]
        (cons form (interpolate-worker (if atom? (subs rest 1) rest)))
        (cons (subs s 0 2) (interpolate-worker (subs s 2))))))
  ([#^String s]
    (let [start (max (.indexOf s "~{") (.indexOf s "~("))]
      (if (== start -1)
        [s]
        (lazy-seq (cons
		   (subs s 0 start)
		   (interpolate-worker (subs s start) (= \{ (.charAt s (inc start))))))))))

(defmacro interpolate-s
  [s]
  `(str ~@(interpolate-worker s)))