Re: Sets

Article View: comp.lang.modula2

Article #3896

#3896

From: Gernot Heiser
Date: Wed, 14 Oct 1987 14:41

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In article <INFO-M2%87093023532046@UCF1VM> Info-Modula2 Distribution List <INFO-M2%UCF1VM.bitnet@jade.berkeley.edu> writes:
>Wirth created the idea of a bitset because it would be easy to implement
>a very efficient way to do sets the size of the computer's word.  This
>means sets are likely to be 8, 16 or 32 bits, possibly other sizes,
>depending on the implementation.

I rather believe that this was done to support bit-fiddeling in Modula-2, since
BITSETs aren't really good for anything else. None of Wirth's compilers support
sets bigger than BITSETs. In this sense, a Modula-2 set is not an abstract data
type but an image of a machine word. The question is  whether they ought  to be
called "sets".
-- 
Gernot Heiser                      Phone:       +41 1/256 23 48
Institute for Integrated Systems   CSNET/ARPA:  heiser%ifi.ethz.ch@relay.cs.net
ETH Zuerich                        EARN/BITNET: GRIDFILE@CZHETH5A
CH-8092 Zuerich, Switzerland       EUNET/UUCP:  {uunet,...}!mcvax!ethz!heiser

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Path: arc1-ca.pugleaf.net!utzoo!mnetor!uunet!mcvax!cernvax!ethz!heiser
From: heiser@ethz.UUCP (Gernot Heiser)
Newsgroups: comp.lang.modula2
Subject: Re: Sets
Message-ID: <213@bernina.UUCP>
Date: Wed, 14-Oct-87 10:41:44 EDT
Article-I.D.: bernina.213
Posted: Wed Oct 14 10:41:44 1987
Date-Received: Sun, 18-Oct-87 21:36:32 EDT
References: <INFO-M2%87093023532046@UCF1VM>
Reply-To: heiser@bernina.UUCP (Gernot Heiser)
Organization: ETH Zuerich, Switzerland
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