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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: What would you like in Ada202X?
Date: Sat, 30 Jun 2012 14:34:10 +0200
Organization: cbb software GmbH
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Date: 2012-06-30T14:34:10+02:00
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On Sat, 30 Jun 2012 12:00:13 +0000 (UTC), Brian Drummond wrote:

> One obvious problem with an extensible set of operators, in an operator 
> precedence grammar, is assigning the precedence level of new operators.

Ada actually solved that by making associations of operators in question
illegal. E.g. a or b and c. "or" cannot share argument with "and".

> Given that ways can be found to assign precedence to new operators, why 
> are extensible operators not found in more languages that allow 
> overloading?

Depends on the syntax. Unicode characters, which are not letters are easy.
Operators conflicting with identifiers will impose a serious problem.

> It would seem to be a useful way to add expressibility, and 

http://en.wikipedia.org/wiki/Mathematical_operators_and_symbols_in_Unicode

A subset or all of them would suffice.

> I can't see any fundamental drawbacks. 

Code review and maintainability problems. The set of symbols cannot be
infinite.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de