I chose to ignore the pedantry on what is and isn't a quicksort :) Hoare's original algorithm has been mutated several times, and I think it's subjective which of those mutations deserves the name and which doesn't. Especially in high-level languages that encourage programmers to ignore low level concerns of space usage. Wikipedia calls the copying version a 'simple' quicksort (http://en.wikipedia.org/wiki/Quicksort#Simple_version), so I went with that title. I think it's equally valid to call the in-place quicksort a destructive quicksort, like the difference between reverse and nreverse in Common Lisp.