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From: "Randy Brukardt" <randy@rrsoftware.com>
Subject: Re: Ada grammar rules for names too permissive?
Date: Sat, 5 Jan 2019 02:45:26 -0600
Date: 2019-01-05T02:45:26-06:00	[thread overview]
Message-ID: <q0pqr6$u5t$1@franka.jacob-sparre.dk> (raw)
In-Reply-To: q0n77h$2e4$1@gioia.aioe.org

"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message 
news:q0n77h$2e4$1@gioia.aioe.org...
> On 2019-01-03 23:39, olivermkellogg@gmail.com wrote:
>> On Tuesday, January 1, 2019 at 9:44:17 AM UTC+1, Dmitry A. Kazakov wrote:
>>> [...]
>>>        Never push semantic rules into syntax.
>>
>> I'm not so sure about that:
>> A nice feature of ANTLR is that is supports semantic predicates which can 
>> be embedded in the grammar.
>> For example, using sem preds on the basis of symbol tables would permit 
>> discerning among indexed_component, type_conversion, function_call.
>
> In presence of overloading, really? Anyway, I see no use in such a 
> distinction in general.

Right. That might work in other languages, but in Ada that is a very complex 
algorithm. You'd think that the lack of object overloading would help, and 
it does, but not enough, since you can have a function that returns an array 
that is then indexed, as opposed to a function that returns an 
access-to-function. They both could look like:
     F (1) (2)

And you don't want the grammar to be too smart, simply because hand-written 
error messages are almost always better than automatically generated ones, 
once you get past the trivial (missing punctuation).

                          Randy.




  reply	other threads:[~2019-01-05  8:45 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-29 18:20 Ada grammar rules for names too permissive? olivermkellogg
2018-12-31 21:45 ` Randy Brukardt
2019-01-01  8:44   ` Dmitry A. Kazakov
2019-01-01 19:49     ` Stephen Leake
2019-01-01 20:42       ` Dmitry A. Kazakov
2019-01-02 19:21         ` Stephen Leake
2019-01-02 20:47           ` Dmitry A. Kazakov
2019-01-03 21:45             ` Stephen Leake
2019-01-03 22:34               ` Jere
2019-01-05 18:46                 ` Stephen Leake
2019-01-07 11:11                   ` J-P. Rosen
2019-01-08 18:58                     ` Stephen Leake
2019-01-04  8:53               ` Dmitry A. Kazakov
2019-01-03 22:39     ` olivermkellogg
2019-01-04  8:58       ` Dmitry A. Kazakov
2019-01-05  8:45         ` Randy Brukardt [this message]
2019-01-05 18:50       ` Stephen Leake
2019-01-01 19:46   ` olivermkellogg
2019-01-03 22:36     ` Randy Brukardt
2019-01-01 19:46 ` Stephen Leake
2019-01-01 21:03   ` olivermkellogg
2019-01-02 19:42     ` Stephen Leake
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