Re: [Chicken-users] need help with hygienic macros

[Peter Bex]

On Sun, May 12, 2013 at 06:57:12PM +0200, Jörg F. Wittenberger wrote:
> The idea is to have a definer, `deftig` here, which only abstracts the
> argument list of the defined procedure away.  Here a literal of the
> original macro (as used in a limited/extended XSLT implementation to be
> changed).
> 
> (define-macro (define-transformer symbol . body)
>  `(define (,symbol
>            place
>            message
>           root-node
>            variables
>           namespaces
>            ancestor
>            self-node
>            nl
>            mode-choice
>            proc-chain
>            ) . ,body))
> 
> The code references those parameters by their name, with all
> the downsides of unhygienic macros.

This is indeed fundamentally unhygienic.

> To get rid of the predefined-to-be-kept-in-head list of arguments,
> I want better macros.  All arguments not changed by keyword to
> `xml-walk-down` (which would be `foo` or `gosh` in my example) shall
> just use the values from the enclosing `deftig`.  (Let alone that I can
> probably sort out keyword-value-pairs from `foo`.)  `gosh` BTW
> simulates a macro to access a parameter from the procedure defined
> by `deftig`.  I don't mind it being either `gosh` or `(gosh)`; a one-time
> change in the source doesn't matter.  BUT the actual argument list
> of procedures defined by `deftig` is supposed to change without
> touching every use of `deftig`.  Therefore access to those arguments
> shall be done by sub-macros (reasonably) available (only) within
> the body of `deftig`-defined procedures.

That does sound a lot like parameters.  Why not simply parameterize
the parameters based on arguments to your macros?

Cheers,
Peter
-- 
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