2d.clj

(def puzzle [ 3 0 0 0 0 5 0 1 0
              0 7 0 0 0 6 0 3 0
              1 0 0 0 9 0 0 0 0
              7 0 8 0 0 0 0 9 0
              9 0 0 4 0 8 0 0 2
              0 6 0 0 0 0 5 0 1
              0 0 0 0 4 0 0 0 6
              0 4 0 7 0 0 0 2 0
              0 2 0 6 0 0 0 0 3 ])

(defn index-of [pos]
  (let [[file rank] pos
        x (- (int file) (int \A))
        y (- (int rank) (int \0))]
    (+ x (* 8 y))))

(index-of "A0")