nests.clj

;; binary-like count with n 'bits' which can have values between from and to
;; e.g. (permutations 3 0 3) -> ([0 0] [0 1] [0 2] [1 0] [1 1] [1 2] [2 0] [2 1] [2 2])
(defn permutations [n from to]
  (let [symbols (into [] (take n (repeatedly gensym)))
         ranges (take n (repeatedly #(into [] (range from to))))
         bindings (into [] (interleave symbols ranges))]
    (eval `(for ~bindings ~symbols))))