Re: Why context-free?

Tony Finch <dot@dotat.at>
13 Oct 2005 18:14:55 -0400

          From comp.compilers

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[14 later articles]
| List of all articles for this month |

From: Tony Finch <dot@dotat.at>
Newsgroups: comp.compilers
Date: 13 Oct 2005 18:14:55 -0400
Organization: dotat labs
References: 05-10-053 05-10-055 05-10-064 05-10-070
Keywords: parse, errors

nmm1@cus.cam.ac.uk (Nick Maclaren) wrote:
>
>That is what two-level (van Wijngaarden) grammars were designed for
>but, as I said, I know of no comprehensible description. I have found
>nothing outside the "program proving" area that can handle scoping
>etc., and it is a lifetime task to extract useful information from the
>morass of obfuscated drivel that surrounds it.


The impression I got from reading the revised report on Algol 68 was that
the grammar involved a lot of fiddly programming at the wrong level of
abstraction - it wasted effort on recursive definitions of numerals, for
example. A good formalism should make things clearer, but the vW grammaer
is just obscure. Furthermore it has a reputation for being brittle - the
grammar was difficult to change as the language was refined.


Modern programming language theory doesn't generally bother itself with
syntax, probably because the type theory is interesting and complicated
enough without getting mired in low-level irrelevance.


Tony.
--
f.a.n.finch <dot@dotat.at> http://dotat.at/
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