Re: How to handle operator of undefined associativity

glen herrmannsfeldt <gah@ugcs.caltech.edu>
Wed, 12 May 2010 22:44:18 +0000 (UTC)

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Related articles
[6 earlier articles]
Re: How to handle operator of undefined associativity cr88192@hotmail.com (BGB / cr88192) (2010-05-05)
Re: How to handle operator of undefined associativity gah@ugcs.caltech.edu (glen herrmannsfeldt) (2010-05-05)
Re: How to handle operator of undefined associativity cfc@shell01.TheWorld.com (Chris F Clark) (2010-05-06)
Re: How to handle operator of undefined associativity sh006d3592@blueyonder.co.uk (Stephen Horne) (2010-05-07)
Re: How to handle operator of undefined associativity pat@jantar.org (Patryk Zadarnowski) (2010-05-10)
Re: How to handle operator of undefined associativity alex.colvin@valley.net (mac) (2010-05-12)
Re: How to handle operator of undefined associativity gah@ugcs.caltech.edu (glen herrmannsfeldt) (2010-05-12)
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From: glen herrmannsfeldt <gah@ugcs.caltech.edu>
Newsgroups: comp.compilers
Date: Wed, 12 May 2010 22:44:18 +0000 (UTC)
Organization: Aioe.org NNTP Server
References: 10-05-006 10-05-067
Keywords: syntax, comment
Posted-Date: 13 May 2010 13:01:22 EDT

mac <alex.colvin@valley.net> wrote:
>> > should user be allowed to write multiple not


>> > not not not ( expr );
>> > not not ( expr );


> Infamously, Algol 60 disallowed "not not", leading to an error
> message not not not Algol.


I believe Fortran still doesn't allow it, though there have
been some changes over the years as to what is allowed.


Traditionally, two operators could not be adjacent, so that
unary negation following a binary operator required parentheses.
Nesting of unary operators (+, -, .NOT.) also required, and I
believe still does, parentheses.


I don't believe that the Fortran error message comes out a
above, though.


-- glen
[Depends on the compiler. -John]

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