Using syntax/loc with ellipsis

[sora22]

@LiberalArtist

If, instead, you are manipulating the actual values at runtime, you should take a look at 1.2.6 Contracts on Macro Sub-expressions.

I am, however I am working with a colleague who has already created contracts which I would have to essentially decompose and reapply to the various arguments (its easier to just redirect the syntax highlighting in this particular case). I tried this since it seems to be one proper way to achieve the granular highlighting I'm looking for, but I appear to still be running into similar issues I've had previously in regard to syntax highlighting.

@ryanc

One solution is to use a helper macro that takes the original syntax as an argument:

(define-syntax (example stx)
  (syntax-parse stx
    [(_ val:expr ...)
     #`(begin
         (process/loc val #,stx)
         ...)]))

(define-syntax (process/loc stx)
  (syntax-parse stx
    [(_ val:expr orig-stx)
     (syntax/loc #'orig-stx
       (process val))]))

I did get this to work when using "stx" as the location expression, but as expected it highlights the entire expression rather than the specific subexpression. I was hopeful that using the values of the ellipsis as the location expression would work, however when using them as the location expression I seemed to be causing some inordinate amount of work somewhere (I've never waited longer than 30 seconds to a minute before killing the program, so maybe it will terminate but it's still excessive).

The final thing I've tried since is using with-handlers to re-raise the exception with a srcloc. This appears like it would work if I could differentiate which contract raised the exception with the predicate. I haven't looked too deeply into this yet, so maybe I'm just not aware of how to differentiate them.

For the time being I think I'll use the helper macro suggested by @ryanc but I am still looking for a way to highlight specific expressions. If I can't figure out a way to differentiate which contract raised the exception I'll probably attempt to combine expr/c with with-handlers next? Not the most elegant solutions unfortunately...

By the way, thank you all for your help in trying to figure this out, its very appreciated