ANSI Common Lisp  3 Evaluation and Compilation 3.7 Destructive Operations 3.7.2 Transfer of Control during a Destructive Operation
3.7.2.1 Examples of Transfer of Control during a Destructive Operation
The following examples illustrate some of the many ways in which the
implementation-dependent nature of the modification can manifest
itself.
(let ((a (list 2 1 4 3 7 6 'five)))
(ignore-errors (sort a #'<))
a)
 (1 2 3 4 6 7 FIVE)
OR(2 1 4 3 7 6 FIVE)
OR(2)
(prog foo ((a (list 1 2 3 4 5 6 7 8 9 10)))
(sort a #'(lambda (x y) (if (zerop (random 5)) (return-from foo a) (> x y)))))
(1 2 3 4 5 6 7 8 9 10)
OR(3 4 5 6 2 7 8 9 10 1)
OR(1 2 4 3)
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