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Re: Perl6 grammar

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Luke Palmer
June 17, 2002 13:32
Re: Perl6 grammar
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On Mon, 17 Jun 2002, Melvin Smith wrote:

> I moved this to perl6-internals since that seems to include
> most of the people actually interested in implementation.
> (given 0 responses to Dan's p6-lang post)
> Dan writes to perl6-language:
> # We're looking for folks to work on the first cut perl 6 parser over
> # on perl6-internals. All you need is a good knowledge of perl 5 (which
> # is our first cut implementation language) and a willingness to dig
> # through the Apocalypses and Exegeses. (Well, that and not minding the
> # first version likely getting tossed out when we do the final
> # implementation... :)

Speaking of which, I'm interested.

> 1) I hear some people throwing around recursive descent:
> Ok, when you talk rec-descent it is useful to define how much
> lookahead you need. There are tools available that accelerate
> LL(k) parser development, (pccts, antlr). I had a strange dream
> that pccts even generates Perl but I've not looked at it in a while
> to confirm it.

I think they were talking about Damian's Parse::RecDescent, just because 
it's very versatile and a lot easier to work with than yacc.  I think this 
is a good idea, as it integrates the parser and the lexer like Larry said 
would happen.  Plus, if we're first-cutting in perl, this is definitely 
our best bet. If not, well, out of the question.

> 3) Using the tools from (2) rewrite the bootstrap in Perl6.
> (Repeat, please don't write it by hand)

What about Parrot?  Will it be sufficiently full-featured (regexes and 
such) by that time to pull it off?

> Notice I made no mention of the lexer. From what I gather, Larry wished
> there to be less ambiguities in Perl6 as to shrink the workload of the lexer.
> I've yet to really study Perl6 enough to know this is true, but I trust 
> Larry. :)

I got the opposite impression.  He's said things like the parser and lexer 
will no longer be considered seperate entities.  And his quote in response 
to my first post to perl6-language:

"If strain on the lexer were a design criterion, I blew it long ago."


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