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Re: Fix nreverse
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From: |
Stefan Monnier |
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Subject: |
Re: Fix nreverse |
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Date: |
Wed, 21 May 2014 13:17:28 -0400 |
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User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.4.50 (gnu/linux) |
> That the sequence is mutated is not an implementation detail. It is a
> side effect that should be documented as part of the interface.
> (let ((lst '(1 2 3)))
> (message "Reversed: %s" (reverse lst))
> (message "Original: %s" lst)
> (message "NReversed: %s" (nreverse lst))
> (message "Original: %s" lst))
> ;; Output:
> ;; Reversed: (3 2 1)
> ;; Original: (1 2 3)
> ;; NReversed: (3 2 1)
> ;; Original: (1)
This last "Original" value should not be depended upon by the user.
Stefan