[racket] querying for compile-time information

From: Ryan Culpepper (ryanc at ccs.neu.edu)
Date: Thu Sep 9 17:21:16 EDT 2010

One way is a compile-time table. See, for example, the implementation of 
typed scheme/racket:


Except instead of being indexed by identifier, the table should be 
indexed by module. Probably the simplest way to represent a module is by 
its resolved module path (path/symbol, not the structure). You can get 
the resolved module path via #%variable-reference.

(define-syntax-rule (require-permission perm)
    (let* ([this-module
            (resolved-module-path-name this-module)])
      (hash-set! the-table
                 (cons 'perm (hash-ref the-table key null))))))

You can use (dynamic-require mod (void)) to *visit* a module (and thus 
have it register itself in the compile-time table) without running it.


On 09/09/2010 02:56 PM, Danny Yoo wrote:
> I'm trying to figure out how to query a module for compile-time
> information.  I've got some toy code here:
>       http://github.com/dyoo/permissions
> Basically, I want to annotate a module with permissions that the
> module requires.  I'm defining a permission to be a literal string for
> the moment.  I want to have a way of querying a module, later on, for
> those permissions.  For example, the open-image-url.rkt module here:
>      http://github.com/dyoo/permissions/blob/master/t/open-image-url.rkt
> says that it requires network access.  I'd like to have my query module:
>      http://github.com/dyoo/permissions/blob/master/query.rkt
> be able to grab the set of permissions that a module says that it needs.
> Doing this at runtime is something I know how to accomplish, by having
> my require-permission macro introduce a 'permissions binding.
> However, I don't want to do it that way: I want to grab this
> information without evaluating the run-time portion of a module.
> I started hacking at this on my compile-time branch
> (http://github.com/dyoo/permissions/tree/compile-time) but I'm getting
> stuck.  In particular, I don't quite know how to get my query.rkt
> module to communicate with the record.rkt module.  Can someone give
> pointers on what I should be looking at?
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