[racket] Lifting submodules

From: Greg Hendershott (greghendershott at gmail.com)
Date: Tue Sep 17 13:22:58 EDT 2013

> I want to write a macro which generates submodules and then possibly
> requires them. This is so that can easily use another language (TR)
> for the expression.
> If all uses of the macro are at the top-level/module-level this is
> easy and I can expand out to something like:
> (begin
>   (module new-mod typed/racket <expr and provides>)
>   (require 'new-mod)
>   <use exports>)

Easy... except I can't get even that to work. Even used at the top-level.

I tried because there's a StackOverflow question about this:


I've been trying to answer it, but having one of those humbling
experiences where I wonder how much I've really learned about macros,
after all.  I distilled it to just:

#lang racket
(define-syntax (define-modularize stx)
  (syntax-case stx ()
    ([_ thing-name mod-name]
         (module mod-name racket
           (define thing-name #t)
           (provide thing-name))
         (require 'mod-name)))))

(define-modularize foo foo-mod)
;; (require 'foo-mod)
foo ;; => foo: unbound identifier in module

Only if the previous line with the require is uncommented, does it
work. IOW the module and thing define/provide seem just fine, it's the
require that is not working. Why?

I've thought about it, used the stepper in DrRacket, tried everything
I can think of -- but can't get it to work.

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