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All arrays can be adjustable?
- To: Cyphers@YUKON.SCRC.Symbolics.COM
- Subject: All arrays can be adjustable?
- From: Daniel L. Weinreb <DLW@ALDERAAN.SCRC.Symbolics.COM>
- Date: Wed, 20 May 87 11:31 EDT
- Cc: email@example.com
- In-reply-to: <870519221837.3.CYPHERS@RAVEN.S4CC.Symbolics.COM>
Date: Tue, 19 May 87 22:18 EDT
From: Scott Cyphers <Cyphers@YUKON.SCRC.Symbolics.COM>
Date: Tue, 19 May 87 21:34 EDT
From: David A. Moon <Moon@STONY-BROOK.SCRC.Symbolics.COM>
Date: Tue, 19 May 87 19:03:33 MDT
From: firstname.lastname@example.org (Sandra J Loosemore)
It's definitely wrong for make-array to randomly return adjustable arrays
when the user doesn't specifically ask for them.
I disagree. See below.
I mopstly agree with you, but the bottom of page 28 seems to imply that
you can make arrays which are not to be adjusted, and this is one of the
properties of simple arrays.
"and is not to have its size adjusted" is just another ambiguous phrase.
I read this to mean "and its caller is not allowed to assume that it
would work to adjust its size"; that is, it makes no promises that
adjusting the size would work.
There is no question what the intention of the writers of CLtL was. The
idea of "simple" arrays was to provide a way for stock hardware
implementations to implement simpler arrays more cheaply, without making
any impositions on architectures in which there's no extra cost for more
complex arrays. The wording in CLtL was intended to convey this idea,
but apparently it falls short.
Yes, it might be useful to have a feature that provides for an array
that is guaranteed to signal an error if there is an attempt to adjust
it. However, CL has no such feature, and I think it's only slightly
useful. Arrays have enough features as it is; you have to draw the line