[racket] Macros that use local-require (hygiene issues?)

From: Spencer Florence (spencer at florence.io)
Date: Thu Nov 6 16:29:06 EST 2014

As I play with that example I see that changing #'(let () ...) to #'(begin
...) fixes the issue. Unfortunately in my actual program I can't do that.
Here is an example more akin to the context I'm working in, where that fix
doesn't work:

#lang racket
(provide a)
(define a 1)

;; make the submodule
(define-syntax (mod stx)
  #'(module* R racket
      (require (submod ".." T))
      (test-binding (submod ".."))))

;; defines the requiring macro
(module T racket
        (provide test-binding)
        (require (for-syntax syntax/parse))
        (define-syntax (test-binding stx)
          (syntax-parse stx
            [(_ path)
             #'(begin (require path) a)])))
;; go

On Thu Nov 06 2014 at 3:09:28 PM Spencer Florence <spencer at florence.io>

> Hi All,
> I've been struggling to have a macro be given a path then require
> something from that path. The following code produces and "Unbound
> Identifier" error, although I would expect it to evaluate to 1. Could
> someone provide insight into what is going on?
> #lang racket/load
> ;;provider
> (module T racket
>   (provide a)
>   (define a 1))
> ;; requirer
> (module R racket
>   (require (for-syntax syntax/parse))
>   (define-syntax (test-binding stx)
>     (syntax-parse stx
>       [(_ path)
>        #'(let () (local-require (only-in path a)) a)]))
>   (test-binding 'T))
> ;; go
> (require 'R)
> P.S. I attempted to do this with `dynamic-require,` but that failed
> because in my actual program `path` is sometimes `(submod "..")`, which
> caused an error about not having a base path.
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