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From: ok@goanna.cs.rmit.oz.au (Richard A. O'Keefe)
Newsgroups: comp.lang.misc
Subject: Re: comparison: was He's not the only one at it again!
Message-ID: <3503@goanna.cs.rmit.oz.au>
Date: 2 Aug 90 08:03:10 GMT
References: <25630@cs.yale.edu> <58091@lanl.gov> <3478@goanna.cs.rmit.oz.au> <25696@cs.yale.edu>
Organization: Comp Sci, RMIT, Melbourne, Australia
Lines: 30

In article <25696@cs.yale.edu>, zenith-steven@cs.yale.edu (Steven Ericsson Zenith) writes:
> My intent was to point out that the equality symbol is widely used
> with a quite distinct meaning in general (outside of Computer
> Science): a = b meaning "a is equal to b" as opposed to a := b which
> is untainted by any other meaning that I know of.

:= has been used in mathematics; pronounce it "is defined as".
(You may have seen {small Delta above equal} or {equal sub "def"}
used for the same purpose.)  This is not _too_ remote from the Algol use.

Fortran wasn't able to use := for the simple reason that 026 keypunches
had no colon (:, <, >, aren't in the BCD character set).  Burroughs had
a variant of BCD which was designed for Algol, it even had <= as a single
character.  Algol was able to use := because Algol drew a distinction
between "the publication language" (however fancy a typesetter wanted to
make it), "the reference language" (in which all keywords and operators
are construed as single characters) and the hardware language"
which is machine-dependent.  I hate to reveal this, but there is no
reason in principle why one couldn't have a hardware language for Algol 60
where := was represented by = and = was represented by .EQ. (one might
also want .BEGIN., .END., .IF., and so on).  Was Algol 68 the last
standardised language to try to maintain the distinction between how a
programming language was to be printed for human consumption and how it
may be prepared for a computer in a machine-dependent way?  (Dare I
mention Point stropping, Case stropping, and the others?)

-- 
Distinguishing between a work written in Hebrew and one written in Aramaic
when we have only a Latin version made from a Greek translation is not easy.
(D.J.Harrington, discussing pseudo-Philo)