gistfile1.clj

;;; Example from 'Applicative Programming with Effects' by McBride & Paterson

(use 'clj-control.applicative)
(use 'clj-control.core)
(use 'clj-control.utils)

(defn transpose
  ([matrix]
     (if (empty? matrix)
       (repeat '())
       (let [xs  (first matrix)
             xss (rest matrix)]
         (af-*
          (af-* (repeat (count xs) (curry 2 cons)) xs)
          (take (count xs) (transpose xss)))))))

(def *res*  (transpose '((1 2 3) (4 5 6) (7 8 9))))

(doseq [r *res*]
  (print "[")
  (doseq [c r]
    (print (str " " c) ))
  (println " ]"))

;; [ 1 4 7 ]
;; [ 2 5 8 ]
;; [ 3 6 9 ]