Article View: comp.lang.modula2
Article #3823Re: Number of elements in a set
From: joel
Date: Mon, 14 Sep 1987 21:56
Date: Mon, 14 Sep 1987 21:56
25 lines
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1869 bytes
Pascal's set constructors are untyped, and there are cases where context iss
insufficient to determine at compile time the boundaries of a set.
Most implementations thus implement sets of some small, fixed, size (like 16,
32, 128, or 256 elements). The UCSD implementations go to some pains to allow
dynamically sized sets up to 4096 elements (8-bit microcomputers can deal with
256 16-bit words without too much grief).
Modula-2's set constructors are typed, and therefore the size of the set is
always known at compile time.
Many implementations nonetheless implement sets as the word size of the
machine, because then it's easy to generate single machine instructions. It
is not hard to implement sets of effectively unbounded size; further, it is
usually more efficient, and certainly more readable and useful to have large
sets than to simulate this with the corresponding user code.
One can only hope that the eventual ISO standard will say something useful
about sets, like you can have at least as many elements as, say, MAXINT. But
people who haven't implemented such tend to vote against inclusion of such
language, so don't count on it.
- Joel McCormack {ihnp4 decvax ucbvax allegra}!decwrl!joel
joel@decwrl.dec.com
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Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: arc1-ca.pugleaf.net!utzoo!mnetor!uunet!seismo!husc6!hao!boulder!sunybcs!rutgers!ucla-cs!zen!ucbvax!DECWRL.DEC.COM!joel From: joel@DECWRL.DEC.COM Newsgroups: comp.lang.modula2 Subject: Re: Number of elements in a set Message-ID: <8709142056.AA10394@vulcan.dec.com> Date: Mon, 14-Sep-87 17:56:57 EDT Article-I.D.: vulcan.8709142056.AA10394 Posted: Mon Sep 14 17:56:57 1987 Date-Received: Wed, 16-Sep-87 00:44:23 EDT References: <8709140824.AA21380@cayuga.cs.rochester.edu> Sender: daemon@ucbvax.BERKELEY.EDU Organization: The ARPA Internet Lines: 25