[plt-scheme] macro writing

> SUGGESTION ONE:
> Separate the definitions manually.  Match on the following
pattern initially:
> 
> (syntax-rules ()
>   ((_ n1 (any-names ...) e1 e2 ...)
>    <code here>))
> 
> And in <code here>, write code to manually search through
(syntax
> (any-names ...)) for the keyword "locals".  Then you can
construct
> separate lists or syntax objects for arguments and local
definitions.

Hi,

Ok, I have done the following. It works, but I am looking for
some suggestions how to simplify it? My problem is with the
get-local-init function. I would like to replace it with a
map but
DrScheme always reports an error that I am supplying a syntax 
and not a list. Any idea how to avoid this problem?

Another question: When I expand it to check I get the
following error:

> (expand-once (defun a1 () (+ 1 2)))
define: not allowed in an expression context in: 
(define (a1) (let* () (+ 1 2)))

So I get the right expansion, but reports the error.

Thanks for any help,

Peter

P.S: Here is the code. (The per sign (/) separates arguments
and local variables.)
---------------------------------------------------------------------------------

(define-syntax defun
  (letrec
      ((get-args
        (lambda (args)
          (syntax-case args (/)
            (() (syntax ()))
            ((/ a1 ...) (syntax ()))
            ((a2 a3 ...) (cons (syntax a2) (get-args (syntax
(a3 ...)))))
          )
        )
       )
       (get-local-init
        (lambda (args)
          (syntax-case args ()
            (() (syntax ()))
            ((a2 a3 ...) (cons (list (syntax a2) #f)
(get-local-init (syntax (a3 ...)))))
            ((a1 ...) (list (list (syntax (a1 ...)) #f)))
          )
        )
       )
       (get-locals
        (lambda (args)
          (syntax-case args (/)
            (() (syntax ()))
            ((/ a1 ...) (get-local-init (syntax (a1 ...))))
            ((a2 a3 ...) (get-locals (syntax (a3 ...))))
          )
        )
       )
       
      )
      
    (lambda (x)
      (syntax-case x ()
        ((_ n1 (args ...) e1 e2 ...)
         (with-syntax
             (((new-args ...) (get-args (syntax (args ...)))))
           (with-syntax
               (((new-locals ...) (get-locals (syntax (args
...)))))
             (if (null? (syntax (new-locals ...)))
               (syntax (define (n1 new-args ...) e1 e2 ...))
               (syntax (define (n1 new-args ...)
                         (let* (new-locals ...)
                         e1 e2 ...)))
             )
           )
         )
        )
      )
    )
  )
)

(defun a1 () (+ 1 2))
(defun a2 (a) (+ 1 a))
(defun a3 (a b) (+ a b))
(defun a4 (a b c) (+ a b c))
(defun a5 (/) (+ 2 3))
(defun a6 (/ a) (+ 2 3))
(defun a7 (/ a b) (+ 2 3))
(defun a8 (/ a b c) (+ 2 3))
(defun a9 (a b /) (+ a b))
(defun aa (a b / c) (+ a b))
(defun ab (a b / c d) (+ a b))
(defun ac (a b / c d e) (+ a b))



_______________________________________________________________________________
Élvezd az internet nyújtotta szabadságot! Vásárolj kényelmesen és biztonságosan Virtuális kártyáddal!
[origo] klikkbank diák számlacsomag http://www.klikkbank.hu/lakossagi/termekek/diak_szamlacsomag/index.html