In-reply-to: Timothy Daly <DALY@ibm.com>'s message of 16 April 1987, 14:48:02 EDT
That example isn't a typo. Note that the list (a b) is a member of the
second argument to UNION. This fact is even brought out specifically in
the text as a reason to use :test-not #'mismatch instead of :test
#'equalp.
Pavel