Re: An "open" letter to Karsten Nyblad (and other compiler compiler implementors)

vtsikoza@yahoo.com (Vit)
24 Jun 2005 09:56:22 -0400

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From: vtsikoza@yahoo.com (Vit)
Newsgroups: comp.compilers
Date: 24 Jun 2005 09:56:22 -0400
Organization: http://groups.google.com
References: 05-06-099 05-06-104 05-06-106
Keywords: LALR, parse
Posted-Date: 24 Jun 2005 09:56:22 EDT

"Marcin 'Qrczak' Kowalczyk" <qrczak@knm.org.pl> wrote
> SM Ryan <wyrmwif@tsoft.org> writes:
>
> > # I only wonder, have not languages designers become cleverer in the
> > # recent decades to invent languages that do not require the full
> > # strength of LR(k)?
> >
> > Why not just use LR(k)? Inertia? Methods to avoid the
> > combinatorial explosion of lookaheads have been known for years.
>
> Aren't most grammars useful in practice either LR(1) or not LR(k) at all?
> If lookahead is required, it rarely has a bounded length.


That was exactly the question! With the emphasis on "useful in
practice". Is it still reasonable to invent languages that are not SLR
or LALR, knowing that this is an additional overhead for a parser?


By the way, yet Aho and Ullman notice that any LR(k>0) language is in
fact LR(1). (The dumb conversion only produces too many artificial
production rules).


Vit


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