Seems like this works well enough, where I approximate the
rename-transformer rather than the syntax property.
(define-syntax (mb stx)
(syntax-case stx ()
[(_ . args) (with-syntax ([args (syntax-property #'args 'key
'value)])
#'(other-module-begin . args))]))
On Tuesday, November 28, 2017 at 9:05:07 PM UTC-8, Jack Firth wrote:
>
> What about passing the configuration data to `other-module-begin` via
> keyword arguments or tagged expressions in the body of the
> `(other-module-begin ...)` expansion? Is there a particular reason `mb` and
> `other-module-begin` need to communicate with syntax properties?
>
> On Tuesday, November 28, 2017 at 7:15:50 PM UTC-8, Matthew Butterick wrote:
>>
>> I'm making a #%module-begin macro, but I want to delegate it to an
>> existing one.
>>
>> OK, let's start with a rename transformer:
>>
>> (provide (rename-out [mb #%module-begin]))
>> (define-syntax mb (make-rename-transformer #'other-module-begin))
>> (define-syntax other-module-begin (λ (stx) #'foo))
>>
>> That works, but I also need to pass some extra data to
>> `other-module-begin` that controls how it's configured during this
>> delegation.
>>
>> OK, let's add a syntax property. But wrapping the property around the
>> transformer doesn't work, because a rename transformer is not `syntax?`:
>>
>> (provide (rename-out [mb #%module-begin]))
>> (define-syntax mb (syntax-property (make-rename-transformer
>> #'other-module-begin) 'foo "bar"))
>> (define-syntax other-module-begin (λ (stx) #'foo))
>>
>> ;; syntax-property: contract violation
>>
>>
>> I can wrap the property around the target identifier, but the syntax
>> property doesn't stick:
>>
>> (provide (rename-out [mb #%module-begin]))
>> (define-syntax mb (make-rename-transformer (syntax-property
>> #'other-module-begin 'foo "bar")))
>> (define-syntax other-module-begin (λ (stx) #'foo))
>>
>> (syntax-property #'mb 'foo) ; #f
>>
>>
>> Other possibilities with equivalent effect?
>
>
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