Re: guile and XML (mixp)

[Neil Jerram]

Jon Wilson <address@hidden> writes:

> Hi Neil,
>> Whoever is doing (use-modules (ice-9 syncase)) needs to do (use-syntax
>> (ice-9 syncase)) instead.
>>
> I see this fairly often.  Perhaps there should be some little widget
> in (ice-9 syncase) which says "If you try to use=modules me, you will
> actually get use-syntax instead.).  Or could an argument be made for
> combining use-modules and use-syntax?  Are there any cases where one
> would write a module, and then at some times want to use-modules it,
> and at other times want to use-syntax it, so that the user would need
> to specify which one was wanted?

It's conceivable, but probably quite unlikely.

I'm not sure I like the idea of a module automagically switching its
user's intent from use-module to use-syntax.  That feels too
non-explicit to me.

What seems very reasonable, however, would be a way for a module to
discover whether it is being loaded for use-syntax or use-module, so
that it can emit a warning, or even signal an error, if the use is
inappropriate.

Perhaps something like this...

 (define-module (ice-9 syncase)
   ...
   #:use-hook my-use-hook)

 (define (my-use-hook usage)
   (or (eq? usage #:use-syntax)
       (error "The (ice-9 syncase) module should always be used by
   calling (use-syntax ...), not (use-modules ...)")))

 ...

Does that sound reasonable?

Regards,
     Neil