I believe that run time will be the most plausible use case. I may write macros that refer to struct-procedure names at macro-writing time, but I don't expect to invoke the struct procedures at macro-expansion time. My primary issue is "discoverability:" how can I find out the interface of any struct?
On Thursday, October 28, 2021 at 1:00:15 PM UTC-7 jackh...@gmail.com wrote: > Are you intending to use the struct procedure names at compile time (such > as in a macro) or runtime? > > On Tuesday, October 26, 2021 at 5:02:46 PM UTC-7 bc.be...@gmail.com wrote: > >> I understand why structs are opaque, by default, but I want to discover >> the public interface of some struct type, that is, a list of the procedures >> defined by the struct. >> >> Here is an example. Suppose I want to find out all the procedures defined >> on an instance of the syntax struct >> >> #'42 >> >> Dr. Racket shows an expander clicky that shows some formatted information >> inside the instance : >> >> [image: Screenshot from 2021-10-26 16-51-37.png] >> >> Uncapitializing the names in the display reveals the interface: >> >> (syntax-position #'42) ~~> 790 >> (syntax-span #'42) ~~> 2 >> (syntax-original? #'42) ~~> #t >> >> etc. >> >> I want to discover those procedure names in my racket program, not >> manually by visually inspecting graphics in Dr Racket. >> >> I found this trick for structs that I define: >> >> #lang racket >> (require (for-syntax racket/struct-info)) >> (require racket/pretty) >> >> (struct foo (a b)) >> (begin-for-syntax >> (displayln >> (extract-struct-info >> (syntax-local-value >> #'foo)))) >> >> ~~> >> >> [image: Screenshot from 2021-10-26 16-59-19.png] >> >> but it doesn't work for the syntax type >> >> (begin-for-syntax >> (displayln >> (extract-struct-info >> (syntax-local-value >> #'syntax)))) >> >> ~~> >> >> [image: Screenshot from 2021-10-26 17-00-33.png] >> >> I'd be grateful for advice and an example of how to get the interface of >> "syntax" without Dr Racket and without grovelling docs. >> > -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/racket-users/8e4ca03e-e276-4c42-a662-4fcf7c994387n%40googlegroups.com.
