I started working with this last night, and it simplified the code a lot. I was able to build syntax classes on top of other ones with a lot less worrying about when the slow path would be run. (And uncovered a couple of optimizer bugs in the process).
On Wed, Jun 5, 2013 at 2:05 PM, Ryan Culpepper <ry...@ccs.neu.edu> wrote: > I've implemented what I described earlier, as well as the error on 3D values > in a #:with clause or ~parse right-hand side. > > Pattern variables that come from syntax-parse already acted differently; if > they weren't syntax-valued, they raised errors. All I've done now is turn > some error cases into non-error cases. > > Ryan > > > > On 06/01/2013 11:55 AM, Eric Dobson wrote: >> >> I would say not to implement this just on my behalf. I think it would >> be weird for pattern variables to act differently if they came from >> syntax-parse versus from with-syntax. >> >> On Fri, May 31, 2013 at 2:17 PM, Sam Tobin-Hochstadt <sa...@ccs.neu.edu> >> wrote: >>> >>> On Fri, May 31, 2013 at 4:42 PM, Ryan Culpepper <ry...@ccs.neu.edu> >>> wrote: >>>> >>>> >>>> Note, however, that the syntax class now uses #:attr instead of #:with. >>>> That's the main usability issue I'm worried about with this change. >>>> Following with-syntax's lead, a #:with clause automatically converts its >>>> right-hand side to syntax---even if the result is "3D". That means that >>>> if >>>> you forget that step of the conversion to laziness, you'll probably get >>>> bizarre 3D syntax. I could change #:with to raise an error in some/all >>>> 3D >>>> cases, but that might break existing programs. >>>> >>>> Is anyone out there using syntax-parse to make 3D syntax? >>> >>> >>> I'm sure all the places where I do this are bugs (and it has happened >>> to me), so I'd welcome this error. >>> >>> Sam > > ____________________ Racket Users list: http://lists.racket-lang.org/users
