Euclidean Rhythm generator in Clojure

euclidean.clj

(defn split-seq [s]
  "Extract a tail of all same elements: [1 1 0 0 0] -> [[1 1] [0 0 0]]"
  (let [l (last s)]
    (split-with #(not= l %) s)))

(defn recombine
  "Distribute tail: [[1] [1] [1] [0] [0]] -> [[1 0] [1 0] [1]]"
  ([a b] [a b])
  ([a b c] [a b c])
  ([a b c & more]
     (let [s (concat [a b c] more)
           [head tail] (split-seq s)
           recombined (map concat head tail)
           r-len (count recombined)]
       (if (empty? head)  ;; even pattern (all supbatterns same)
         s
         (apply recombine (concat
                           recombined
                           (drop r-len (drop-last r-len s))))))))

(defn E [k n]
  "Evenly distribute K beats among N subdivisions"
  (let [seed (concat (repeat k [1]) (repeat (- n k) [0]))]
    (flatten (apply recombine seed))))



;; output
> (E 3 6)
(1 0 1 0 1 0)
> (E 3 8)
(1 0 0 1 0 0 1 0)
> (E 4 6)
(1 0 1 1 0 1)
> (E 3 8)
(1 0 0 1 0 0 1 0)
> (E 2 6)
(1 0 0 1 0 0)
> (E 3 4)
(1 0 1 1)
> (E 5 11)
(1 0 0 1 0 1 0 1 0 1 0)