Re: Mixing OO and DB

From: rpost <rpost_at_pcwin518.campus.tue.nl>
Date: Sun, 17 Feb 2008 00:02:14 +0100
Message-ID: <c82a3$47b76b76$839b4533$9257_at_news1.tudelft.nl>


Tegiri Nenashi wrote:

>I'm glad I entertained you, although you are missing the point (as
>usual). What languages on a particular levels of Chomsky hierarcky are
>capable (or rather uncapable of) is not important. Grammar based
>methods are immature (yet?) and there is even no clear concept of
>string transformation. Attribute grammars is as far as the theory got,
>but in practice people put all kind of horrible procedural sideeffects
>inside the curly brakets after each grammar rule.

I think one of the problems with context-free grammars is that the theory doesn't presuppose any kind of syntactic guidance in recognizing the syntax trees. In practice we usually mark our clauses and subclauses explicitly, so the languages we use are more like bracketed languages (a subclass of the context-free languages).

XML gets this right: it more or less assumes the syntactic structure is explicitly present in the documents. Grammar and transformation are really popular for XML. Its one drawback is that it imposes a lexical syntax that is quite hard to read, with its tags and attributes; it would have been better to make surface syntax pluggable so we could use alternatives such as YAML with the tools available for XML.

-- 
Reinier
Received on Sun Feb 17 2008 - 00:02:14 CET

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