Let's make a deal.clj

(defn pick-a-door [doors]
  (nth doors (rand-int (count doors))))

(defn play-the-game [strategy]
  (let [*doors* '(1 2 3)
	*winning-door* (pick-a-door *doors*) ; Computer picks one door to be a winner
	*chosen-door* (pick-a-door *doors*) ; player picks a door
	*remaining-doors* (filter (fn [value]
				    (or (= value *winning-door*)
					(= value *chosen-door*))) *doors*)] ; Of the remaining doors, remove one that is not good
    (if (= strategy :switch)
      (let [second-choice (pick-a-door *remaining-doors*)]
	(if (= second-choice *winning-door*)
	  1.0
	  0.0))
      (if (= strategy :stay)
	(if (= *chosen-door* *winning-door*) ; Staying
	  1.0 ; winning :)
	  0.0))))) ; losing :(

(defn results [strategy]
  (lazy-seq 
   (cons (play-the-game strategy)
	 (results strategy))))

(defn mean [coll]
  (/ (reduce + coll) (count coll))