Re: Can syntax be enough? No need of semantics.

Andy Walker <news@cuboid.co.uk>
Sat, 19 Sep 2009 01:36:00 +0100

          From comp.compilers
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| List of all articles for this month |
From: Andy Walker <news@cuboid.co.uk>
Newsgroups: comp.compilers
Date: Sat, 19 Sep 2009 01:36:00 +0100
Organization: Compilers Central
References: 09-09-062 09-09-067
Keywords: parse
Posted-Date: 21 Sep 2009 15:13:17 EDT

I wrote:
> Never seen a reasonable two-level grammar? Fi!
> [Good point. So why don't we use them? -John]


Good question. Some answers:


    (a) We don't know how to parse them. So we have first to convert
them into simpler grammars, which somewhat defeats the point.


    (b) It's hard work to write one. People who invent languages seem
to prefer to specify an EBNF grammar, or similar, and then add
the semantics by saying in natural language what the rules are.
The result is that no-one knows what C, for example, really is,
as there is no adequately formal specification. Not since the
days when the formal spec was DMR's compiler.


    (c) Fear.


--
Andy Walker
Nottingham


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