(in-ns 'user)

(defn sort-parts
  "Lazy, tail-recursive, incremental quicksort. Works against
  and creates partitions based on the pivot, defined as 'work'."
  [work]
  (lazy-seq
   (loop [[part & parts] work]
     (if-let [[pivot & xs] (seq part)]
       (let [smaller? #(< % pivot)]
         (recur (list*
                 (filter smaller? xs)
                 pivot
                 (remove smaller? xs)
                 parts)))
       (when-let [[x & parts] parts]
         (cons x (sort-parts parts)))))))

(defn qsort [xs]
  (sort-parts (list xs)))

(first (qsort (vec (take 1000000 (iterate dec 999998)))))

No message.
  [Thrown class java.lang.StackOverflowError]

Restarts:
 0: [QUIT] Quit to the SLIME top level

Backtrace:
  0: clojure.lang.LazySeq.sval(LazySeq.java:42)
  1: clojure.lang.LazySeq.seq(LazySeq.java:60)
  2: clojure.lang.RT.seq(RT.java:466)
  3: clojure.core$seq.invoke(core.clj:133)
  4: clojure.core$filter$fn__3830.invoke(core.clj:2469)
  5: clojure.lang.LazySeq.sval(LazySeq.java:42)
  6: clojure.lang.LazySeq.seq(LazySeq.java:60)
  7: clojure.lang.RT.seq(RT.java:466)
  8: clojure.core$seq.invoke(core.clj:133)
  9: clojure.core$filter$fn__3830.invoke(core.clj:2469)
 10: clojure.lang.LazySeq.sval(LazySeq.java:42)
 11: clojure.lang.LazySeq.seq(LazySeq.java:60)
 12: clojure.lang.RT.seq(RT.java:466)
 13: clojure.core$seq.invoke(core.clj:133)
 14: clojure.core$filter$fn__3830.invoke(core.clj:2469)
 15: clojure.lang.LazySeq.sval(LazySeq.java:42)
 16: clojure.lang.LazySeq.seq(LazySeq.java:60)
 17: clojure.lang.RT.seq(RT.java:466)
 18: clojure.core$seq.invoke(core.clj:133)
 19: clojure.core$filter$fn__3830.invoke(core.clj:2469)
 20: clojure.lang.LazySeq.sval(LazySeq.java:42)
 21: clojure.lang.LazySeq.seq(LazySeq.java:60)
 22: clojure.lang.RT.seq(RT.java:466)
 23: clojure.core$seq.invoke(core.clj:133)
 24: clojure.core$filter$fn__3830.invoke(core.clj:2469)
 25: clojure.lang.LazySeq.sval(LazySeq.java:42)
 26: clojure.lang.LazySeq.seq(LazySeq.java:60)
 27: clojure.lang.RT.seq(RT.java:466)
 28: clojure.core$seq.invoke(core.clj:133)
 29: clojure.core$filter$fn__3830.invoke(core.clj:2469)
 30: clojure.lang.LazySeq.sval(LazySeq.java:42)
 31: clojure.lang.LazySeq.seq(LazySeq.java:60)
 32: clojure.lang.RT.seq(RT.java:466)
 33: clojure.core$seq.invoke(core.clj:133)
 34: clojure.core$filter$fn__3830.invoke(core.clj:2469)
 35: clojure.lang.LazySeq.sval(LazySeq.java:42)
 36: clojure.lang.LazySeq.seq(LazySeq.java:60)
 37: clojure.lang.RT.seq(RT.java:466)
 38: clojure.core$seq.invoke(core.clj:133)
 39: clojure.core$filter$fn__3830.invoke(core.clj:2469)
 40: clojure.lang.LazySeq.sval(LazySeq.java:42)
 41: clojure.lang.LazySeq.seq(LazySeq.java:60)
 42: clojure.lang.RT.seq(RT.java:466)
 43: clojure.core$seq.invoke(core.clj:133)
 44: clojure.core$filter$fn__3830.invoke(core.clj:2469)
 45: clojure.lang.LazySeq.sval(LazySeq.java:42)
 46: clojure.lang.LazySeq.seq(LazySeq.java:60)
 47: clojure.lang.RT.seq(RT.java:466)
 48: clojure.core$seq.invoke(core.clj:133)
 49: clojure.core$filter$fn__3830.invoke(core.clj:2469)
 --more--