mars-rovers-basic.clj

(ns mars-rovers.core)

(def dirs [:N :E :S :W])

(def move-dir {:N [0, 1] :E [1, 0] :S [0, -1] :W [-1, 0]})

(defn turn [dir dirs]
  (second
    (drop-while
      (complement #(= % dir))
      (cycle dirs))))

(defn turn-left [dir]
  (turn dir (reverse dirs)))

(defn turn-right [dir]
  (turn dir dirs))

(defn move [x y dir]
  (conj
    (vec
      (map + [x y]
           (move-dir dir)))
    dir))

(defn rover-action [[x y dir] action]
  (cond
    (= action \L) [x y (turn-left dir)]
    (= action \R) [x y (turn-right dir)]
    (= action \M) (move x y dir)))

(defn deploy-rover [start path]
  (reduce rover-action start path))