[racket] pre-announcement for ragg. Request for comments and suggestions

Hi everyone,

I've been developing yet another parser generator generator framework
for Racket.  Since "yapps" is already taken by another project, I'm
calling this thing "ragg", for Racket AST Generator Generator.

ragg is a parsing framework with the design goal to be easy to use. It
includes the following features:

* It provides a #lang for writing extended BNF grammars. A module
written in #lang ragg automatically generates a parser. The output of
this parser tries to follow HTDP doctrine; the structure of the
grammar informs the structure of the Racket syntax objects it
generates.

* The language uses a few conventions to simplify the expression of
grammars. The first rule in the grammar is automatically assumed to be
the starting production. Identifiers in uppercase are assumed to
represent terminal tokens, and are otherwise the names of
nonterminals.

* Tokenizers can be developed completely independently of parsers.
ragg takes a liberal view on tokens: they can be strings, symbols, or
instances constructed with the token function in ragg/support.
Furthermore, tokens can optionally provide location: if tokens provide
location, the generated syntax objects will as well.

* The underlying parser should be able to handle ambiguous grammars.

It's almost ready for release.  I'm in the middle of polishing ragg.
Preliminary documentation can be found at
http://hashcollision.org/ragg.  I'd like feedback on what obvious
functionality I'm missing from the system.  As far as I know, the huge
gaping weakness is a lack of a story about tokenization, which I'm
still trying to figure out, and for this first release, I think I will
need to skip it.  But since I want to make this Pretty Good (as
Insanely Great is probably trademarked), I'd love to hear from other
people what they need from a framework like this.


Hope this helps, and happy new year!