neena and kitallis delve into clj

mars-rover.clj

(ns mars-rover.core)

;
; first: grid size
; 
; rest: pairs of 2 lines each, containing rover agenda.
; 1st line for pair:
; rover starting position on the grid
; 2nd line for pair:
; all instructions to move
;
; X Y D
; L => D
; defn move (for L)
;
; W => X -> X - 1
; N => Y -> Y + 1
; E => X -> X + 1
; S => Y -> Y - 1

(def directions ('W 'N 'E 'S))
(def direction-weights {'W -1 'E +1 'N +1 'S -1})

(def new-direction [position direction]
    (conj (pop position) (nth directions (mod (+ direction (indexOf (last position))) 4))))

(def one-direction [position]
  (let [coord (mod (indexOf direction (last position)) 2)]
    (assoc position coord (+ (get direction-weights (last position)) (nth position coord)))))

(defn move [position instructions]
  (if (empty instructions)
    position
    (let [new_position (case (first instructions)
                         "L" (new-direction position -1)
                         "R" (new-direction position +1)
                         "M" (one-direction position)
                         )]
      (move new_position (rest instructions)))))

(defn parse [rover-agenda]
  ((map read-string (clojure.string/split (first rover-agenda) #" ")) (clojure.string/split (second rover-agenda) #" ")))

(defn display-rover [position]
  (apply println position))

(defn -main
  []
  (let [grid (read-line)]
    (map (fn [ra] (apply println (parse ra))) (partition 2 (take-while (comp not nil?) (repeatedly read-line))))
    ;(map (comp display-rover (partial apply  move) parse) (partition 2 (take-while (comp not nil?) (repeatedly read-line))))
    ))

1. Doesn't work.
2. Doesn't consider Grid boundaries.

/@deobald