partitions

partitions.clj

(defn split-from
  "like split-at but with an offset.
  Usage:
  (split-from 5 7 (range 10)) -->
  [(5 6 7) (8 9)]
  "
  [offset to s]
  (split-at (- to (dec offset))
            (second (split-at offset s))))

(defn partitions
  "partition a seq using a vector of cut points
   Usage:
    (partitions [4 7 14] (range 20)) -->
    ((0 1 2 3 4) (5 6 7) (8 9 10 11 12 13 14) (15 16 17 18 19))
  "
  ([cuts s]
     (partitions cuts s 0))
  ([cuts s offset]
     (cond
      (and (first cuts) s)
      (lazy-seq
       (let [divided (split-from offset (first cuts) s)
             next-offset (+ offset (count (first divided)))]
         (cons (first divided)
               (partitions (next cuts) s next-offset))))
      :else
      (seq [(second (split-at offset s))]))))