From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham
	autolearn_force=no version=3.4.4
X-Google-Thread: 103376,3a1c64628a09855b,start
X-Google-Attributes: gid103376,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news1.google.com!postnews.google.com!p25g2000hsf.googlegroups.com!not-for-mail
From: usenet@leapheap.co.uk
Newsgroups: comp.lang.ada
Subject: Lack of formal syntax undermines Ada
Date: Fri, 11 Apr 2008 02:41:28 -0700 (PDT)
Organization: http://groups.google.com
Message-ID: 
 <e99fb94d-da10-41d2-9f20-7a6ce78d4613@p25g2000hsf.googlegroups.com>
NNTP-Posting-Host: 32.58.34.227
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
X-Trace: posting.google.com 1207906888 7368 127.0.0.1 (11 Apr 2008 09:41:28
 GMT)
X-Complaints-To: groups-abuse@google.com
NNTP-Posting-Date: Fri, 11 Apr 2008 09:41:28 +0000 (UTC)
Complaints-To: groups-abuse@google.com
Injection-Info: p25g2000hsf.googlegroups.com; posting-host=32.58.34.227;
	posting-account=QVLfzAkAAAA63KKDMkjz_X5cKx2FC2Nc
User-Agent: G2/1.0
X-HTTP-Via: 1.0 KNDPXS01
X-HTTP-UserAgent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1;
 .NET
	CLR 1.1.4322; InfoPath.1; .NET CLR 2.0.50727),gzip(gfe),gzip(gfe)
Xref: g2news1.google.com comp.lang.ada:20876
Date: 2008-04-11T02:41:28-07:00
List-Id: <comp.lang.ada>

Ada does not have a formal syntax. The LRM provides "syntax rules"
section by section, then collectively in Annex P. The resulting
woolly grammar is well-known to be ambiguous (e.g. is X:=Y(Z) an
assignment from a function call, array indexing or something
else?). It mixes lexical and syntactical information. It cannot
be used as the input to a parser generator. The interpretation
necessary via other sections of the LRM risks making the language
as a whole indefinite.

Ada is designed for the construction of high-integrity software
by validated compilers. Would it not be better to have formal
Ada lexical and syntactic rules, expressed in regular expression
and BNF format respectively, even if such rules turn out to be
not particularly readable?

As an example, my parser is having trouble with the fragment:
task type TT is
   pragma priority(12);
end TT;
Is this legal Ada95 syntax or not?

Regards,
Chris Noonan