+1 On Wed, Sep 16, 2009 at 7:05 AM, Dave Herman <dher...@ccs.neu.edu> wrote: > Floating an idea: > > I'd love to see an extension to the `parser' form that allows programmers to > define grammar macros. Imagine if you could do something like this: > > (parser > (start Expr) > (end EOF) > (tokens Tokens) > (macros > (define-macro (List x) > [(LPAREN (ListTail x)) > $2]) > (define-macro (ListTail x) > [(RPAREN) '()] > [(x COMMA (ListTail x)) > (cons $1 $3)])) > (grammar > (Expr > [(Expr (List Expr)) > (make-app-expr $1 $2)] > [(LAMBDA ID (List ID)) > (make-lambda-expr $2 $3)] > ;; etc... > ))) > > and imagine the macros would be expanded away as part of the expansion of > the `parser' form. This would give you the ability to define abstractions in > the grammar language in a manner that results in code duplication rather > than sharing. Obviously, it's a bit of a blunt instrument, but in an LALR > framework this kind of duplication is sometimes necessary to avoid > conflicts. > > Perhaps better yet, it'd be cool if these macros could be defined > independently, like match-expanders: > > (define-grammar-expander (ListTail x) > [(RPAREN) '()] > [(x COMMA (ListTail x)) > (cons $1 $3)]) > > Thoughts? > > BTW, who maintains the parser-tools these days? > > Dave > > _________________________________________________ > For list-related administrative tasks: > http://list.cs.brown.edu/mailman/listinfo/plt-dev >
-- Jay McCarthy <j...@cs.byu.edu> Assistant Professor / Brigham Young University http://teammccarthy.org/jay "The glory of God is Intelligence" - D&C 93 _________________________________________________ For list-related administrative tasks: http://list.cs.brown.edu/mailman/listinfo/plt-dev
