There is a sentence in the essay
http://www.jsoftware.com/jwiki/Essays/Quicksort
that reads:
There is an amusing variant that  (in qsort) replaces the first comma
by ; and the second by ,&<

I think it should be changed to

There is an illuminating variant that replaces the first comma by ;
and the second by ,&<

  ] v=: 13 ?...@$ 10
0 7 8 9 2 2 5 5 5 3 8 0 0
  qsort v
+----------------+-+----------------------+
|++-----+-------+|3|+-----------------+-++|
|||0 0 0|++---++|| ||++-----+--------+|9|||
|||     |||2 2|||| ||||5 5 5|+-+---++|| |||
|||     |++---++|| ||||     ||7|8 8|||| |||
|++-----+-------+| ||||     |+-+---++|| |||
|                | ||++-----+--------+| |||
|                | |+-----------------+-++|
+----------------+-+----------------------+

;<S:0 qsort v
0 0 0 2 2 3 5 5 5 7 8 8 9

Probably one of the simplest and best illustrations of how quicksort works.
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