joy-of-clojure-bot.clj

;; Robot from Joy of Clojure, Ch 7

(def bearings [{:x  0 :y  1}   ; move north
               {:x  1 :y  0}   ; move east
               {:x  0 :y -1}   ; move south
               {:x -1 :y  0}]) ; move west
(defn bot [x y bearing-num]
  {:coords [x y]
   :bearing ([:north :east :south :west] bearing-num)
   :forward (fn [] (bot (+ x (:x (bearings bearing-num)))
                        (+ y (:y (bearings bearing-num)))
                        bearing-num))
   :turn-right (fn [] (bot x y (mod (+ bearing-num 1) 4)))   ;; Note this is different from the book
   :turn-left  (fn [] (bot x y (mod (- bearing-num 1) 4)))}) ;; It had (mod (<op> 1 bearing-num)