Using syntax/loc with ellipsis

Questions & Answers
2

Hi, @sora22.

It can be tricky to know "the shape" of these kinds of forms, but it is helpful to remember that syntax/loc is like syntax, i.e. #', but with the source-location data from the stx in the first argument.

So, for example, this works:

#lang racket/base

(require
  (for-syntax
   racket/base
   syntax/parse))

(define-syntax (example stx)
  (syntax-parse stx
    [(_ vals ...)
     #:attr val* (syntax/loc stx (vals ...))
     #'(begin . val*)]))

(example 14)
;=> 14

But that doesn't really answer your question.

I think technically what you want to do, is related to quasisyntax/loc, which is again, like quasisyntax, i.e. #, but with source-location information from the relevant syntax.

Ag, and then I go and talk nonsense. quasisyntax is supposed to be related to "#`". The idea is there, I apologize for being a moron.

So, this also works:

(define-syntax (exampleâ‚‚ stx)
  (syntax-parse stx
    [(_ vals ...)
     #`(begin #,@(quasisyntax/loc stx (vals ...)))]))

Other more experienced Racketeers will be able to give a more definitive answer, because I can only see the "shape" mismatch, but not necessarily the clear rationale for how this should be done.