Thanks, Danny. This fix seems fine if you're willing to dial up to #lang racket, but I'm interested in doing this in *SL, for my students (for whom syntactic consistency is desirable and very important). I suppose I could build my own variant of 2htdp/image which includes the require you give here, and have them require that.
Cheers - Adam On Aug 29, 2012, at 1:08 PM, Danny Yoo wrote: >> This came up perhaps a year ago; I'm writing about pattern matching with the >> color struct that comes with 2htdp/image. It is inconsistent with struct >> matching generally. >> >> In the following excerpt, bar and baz are fine, but foo (commented out) >> causes an error (match: color does not refer to a structure definition): > > > Although it doesn't appear to be documented, the color structure can > be found in mrlib/image-core. So you can do this: > > ;;;;;;;;;; > #lang racket > (require (except-in 2htdp/image color) > (only-in mrlib/image-core color)) > > (match (make-color 3 4 5) > ([struct color (r g b a)] > 'ok)) > ;;;;;;;;;; > > > I think part of what was interfering with what you were doing earlier > is that the 'color' structure isn't exposed as a structure in > 2htdp/image, but instead is exposed as a HTDP-level primitive. > > Good luck! > ____________________ Racket Users list: http://lists.racket-lang.org/users
