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From: Brian Rogoff <bpr@shell5.ba.best.com>
Subject: Re: Operators -> unit analysis
Date: 2000/01/07
Message-ID: <Pine.BSF.4.21.0001070831190.4673-100000@shell5.ba.best.com>#1/1
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 <850jiq$mad$1@nnrp1.deja.com> <3874D0BE.82F04763@Raytheon.com>
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Date: 2000-01-07T00:00:00+00:00
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On Fri, 7 Jan 2000, Ted Dennison wrote:
> In article <853lkg$tgj$1@nnrp1.deja.com>,
>   Robert Dewar <robert_dewar@my-deja.com> wrote:
> > In article <3874D0BE.82F04763@Raytheon.com>,
> 
> > Algol-68 designers regard it as a horrible mistake. One should
> > only rely on precedence of operators where the precedence rules
> > are clear and obvious. This cannot be the case by definition
> > for user defined precedences.
> 
> I think you are saying that in practice it gets to be a mess. I do
> appreciate that. But the above statement would only be true if they are
> truly user-defined. If the operators and precedences are in fact created
> by the user to match existing precedences for established mathematical
> notations, then I think it *would* be clear and obvious to any user. For
> instance, if I make a notation including operators to mimic BNF
> productions (which I am doing, btw), any reasonable user would expect to
> *not* have to put parenthesis around a production's right side just to
> keep the BNF "::=" operator from being evaluated prematurely.

Ted, if this is what you are trying to do, you should take a look at a 
"functional" programming language, like ML or Haskell. These languages 
allow user defined infix operators, and the example you describe is 
well studied in that community. 

-- Brian