Another toy Markov chain generator, this time in Clojure

markov.clj

(def state (ref {}))

(def nonword "\n")

(defn get-words
  []
  (loop [words []]
    (let [line (read-line)]
      (if (nil? line)
	words
	(recur (into words (remove empty? (.split #"\s+" line))))))))

(defn build
  []
  (dosync
   (loop [words (get-words)
	  prefix [nonword nonword]]
     (let [suffixes (get @state prefix [])
	   word (first words)]
       (if (nil? word)
	 (alter state conj {prefix (conj suffixes nonword)})	 
	 (do
	   (alter state conj {prefix (conj suffixes word)})
	   (recur (rest words) (vector (prefix 1) word))))))))

(defn generate
  []
  (loop [prefix [nonword nonword]
	 n 100]
    (if (not (zero? n))
      (let [suffixes (get @state prefix)
	    word (suffixes (rand-int (count suffixes)))]
	(if (not (= word nonword))
	  (do
	    (print word "")
	    (recur [(prefix 1) word] (- n 1))))))))

(build)
(generate)