twenty48.clj

(def remove-zeroes (partial remove zero?))
(def partition-number-sequences (partial partition-by identity))
(def pair-up (partial partition-all 2))
(def pair-partitions (partial mapcat pair-up))
(def sum-of (partial apply +))
(def sum-pairs (partial map sum-of))

(defn concat-zeroes
  [coll]
  (concat coll (repeat 0)))

(def compress-left
  (comp
   concat-zeroes
   sum-pairs
   pair-partitions
   partition-number-sequences
   remove-zeroes))

(def move-row-left (comp (partial take 4) compress-left))

(def move-row-right (comp reverse move-row-left reverse))

(def move-grid-right
  "Moves an entire grid to the right"
  (partial map move-row-right))

(def move-grid-left
  "Moves an entire grid to the left"
  (partial map move-row-left))

(def transpose (partial apply map list))

(def move-grid-down
  "Moves an entire grid down"
  (comp transpose move-grid-right transpose))

(def move-grid-up
  "Moves an entire grid up"
  (comp transpose move-grid-left transpose))