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Issue: ARRAY-TYPE-ELEMENT-TYPE-SEMANTICS (Version 9)
- To: masinter.pa@Xerox.COM
- Subject: Issue: ARRAY-TYPE-ELEMENT-TYPE-SEMANTICS (Version 9)
- From: Jon L White <email@example.com>
- Date: Wed, 11 Jan 89 01:24:32 PST
- Cc: cl-cleanup@Sail.Stanford.Edu
- In-reply-to: masinter.pa@Xerox.COM's message of 10 Jan 89 14:41 PST <890110-144153-6753@Xerox>
re: The benefit of UPGRADE-ARRAY-ELEMENT-TYPE--namely, that it doesn't
CONS as much as the portable definition--seems very small and I don't think
it outweighs the cost.
No, Larry, the issue isn't that it "doesn't CONS as much", but that it
"doesn't CONS *at all*". This kind of issue is critical to some vendors,
such as Inference (which is why Joe Ginder was worrying about the
implicit consing in &rest args and in the sequence functions.)
See CLtL, p292, definition of ARRAY-DIMENSION. Applying the reasoning
that I am now trying to rebut, you would wind up with:
(defun array-dimension (array axis-number)
(elt (array-dimensions array) axis-number))
Why do you suppose that CLtL included ARRAY-DIMENSION in the standard?
How about ARRAY-TOTAL-SIZE? and ARRAY-ROW-MAJOR-INDEX?
-- JonL --