syntax-parse allows you to have multiple ...s, but there's ambiguity about what to do about $ in before or after. You may want "(~and (~not $) before) ... $ after ..."
Jay On Fri, Nov 9, 2012 at 12:45 PM, Spencer Gordon <[email protected]> wrote: > Hello, > > I have been trying to write a macro to allow me to omit some parentheses in > complicated expressions with many complicated sub-expressions in the tail > position. > > (I want the dollar sign to work exactly as it does in Haskell) > > I want to be able to write > > (map (lambda (str) (string-append "Hello, " str)) $ string-titlecase $ list > "Alice "Bob" "Eve") > > > and have it expand to > > (map (lambda (str) (string-append "Hello, " str)) (string-titlecase (list > "Alice "Bob" "Eve"))) > > > My most recent attempt at this macro is > > > (define-syntax $ > (lambda (stx) > (syntax-case stx () > [(before ... $ after ...) > #'(before bs ... (after as...))]))) > > > but this does not work, as I cannot have multiple ellipses in the pattern I > match against in syntax-case. > > I assume it is possible to write such a macro in Racket, but I am at a loss > as to how. > > Can anyone point me in the right direction, please? > > Thanks, > -Spencer Gordon > > ____________________ > Racket Users list: > http://lists.racket-lang.org/users > -- Jay McCarthy <[email protected]> Assistant Professor / Brigham Young University http://faculty.cs.byu.edu/~jay "The glory of God is Intelligence" - D&C 93 ____________________ Racket Users list: http://lists.racket-lang.org/users
