Bubble-sort in Clojure

Following on with my exploration into implementing common sorting algorithms in Clojure, today we have the Bubble-sort. This sort works by iteratively passing through the supplied sequence, swapping the current element with the next if it is comparably greater. The operation is complete when a pass through the sequence does not result in a swap occurring.

(defn- bubble [ys x]
  (if-let [y (peek ys)]
    (if (> y x)
      (conj (pop ys) x y)
      (conj ys x))
    [x]))

(defn bubble-sort [xs]
  (let [ys (reduce bubble [] xs)]
    (if (= xs ys)
      xs
      (recur ys))))

(bubble-sort [3 2 1]) ; [1 2 3]

Looking at the implementation above you will notice we use a reduce operation with a private bubble function which provides us with the pass through the sequence. Upon each pass the result is checked against the input to see if a swap has occurred, in the case of them both being equal we have completed the sorting process.