Clojure code for Pascal's Triangle.

pascals-triangle.clj

(defn pascal 
  "Returns the number in the given row and column of
  Pascal's triangle."
  [row column]
  (cond (= column 1) 1
        (= column row) 1
        (> column row) 0
        :else (+ (pascal (- row 1) (- column 1))
                 (pascal (- row 1) column)))))

(defn make-pascal-triangle 
  "Creates an nxn matrix containing Pascal's triangle."
  [n]
  (vec (for [i (range 1 (inc n))]
         (into [] (for [j (range 1 (inc n))] 
                    (pascal i j))))))

(println (apply str 
                (map #(str % "\n") 
                        (for [row (make-pascal-triangle 5)] 
                          (clojure.string/join " " row)))))