[Chicken-users] misc questions about macros

[Hugo Arregui]

Hi guys,

I'm pretty new to macros, so I want to ask a couple of questions to
sort the things in my brain :-).

1) I think this is an issue regarding expansion time / runtime:

(define (aproc a)
  (* 2 a))

(define-syntax amacro
  (er-macro-transformer
    (lambda (x r c)
      (aproc 1))))

(print (amacro))

works great via csi, but when I try to compile it:

Error: during expansion of (amacro ...) - unbound variable: aproc

        Call history:

        <syntax>          (##core#begin (print (amacro)))
        <syntax>          (print (amacro))
        <syntax>          (amacro)
        <eval>    (aproc 1)     <--


Clarification: This is a simplification, I know I can do this:

(define-syntax amacro
  (er-macro-transformer
    (lambda (x r c)
      '(aproc 1)))) ; I should rename this

But I'm trying to understand whats happening in the first example.

My questions are:
  - I'm guessing the proc isn't available in expansion time. I'm right?
  - How can make this work?

2) I have a macro called "jlambda-field", its signature is:

(jlambda-field (modifiers) type class field-name)

Now, if modifiers contains "static" keyword I want to delegate the
call to static-field macro, otherwise, delegate to field macro. As
static could be in any position in the list, I need to express a "list
contains" pattern. I express that in this way:

(define-syntax jlambda-field
  (syntax-rules (static)
    ((_ (static) type class field-name)
     (static-field () type class field-name))
    ((_ (static modifier ...) type class field-name)
     (static-field (modifier ...) type class field-name))
    ((_ (modifier ... static) type class field-name)
     (static-field (modifier ...) type class field-name))
    ((_ modifiers type class field-name)
     (field modifiers type class field-name))))

This works perfect, but I want to ask, there is a simplified way to do this?

Thanks,
Hugo