gistfile1.clj

(ns sudoku
  (:require [clojure.contrib.seq-utils :as su]))

(defn cross [A B]
  (for [a A b B] (str a b)))

(def rows "ABCDEFGHI")
(def cols "123456789")
(def digits "123456789")

(def squares (cross rows cols))

(def unitlist (concat (for [c cols] (cross rows (str c)))
                      (for [r rows] (cross (str r) cols))
                      (for [rs (partition 3 rows)
                            cs (partition 3 cols)]
                        (cross rs cs))))

(def units (into {} (map (fn [s] {s (filter #(some (partial = s) %) unitlist)}) squares)))

(def peers (into {} (map (fn [s] {s (apply hash-set (for [u (units s) s2
                                                          u :when (not= s2 s)] s2))})
                         squares)))