Dear all:
I've been developing a library that needs some macro coding. As I come
from Common-Lisp and Elisp, I find more pleasing the old-style
define-macro. The following function is used as a part of the result
building of another define-macro:
(define (new-field-mono f-name (default-value null))
(let ((field-name (append-id "-" f-name))
(set-name (append-id f-name "-set!")))
`(begin
(field [,field-name ,default-value])
(define/public (,f-name) ,field-name)
(define/public (,set-name value)
(set! ,field-name value)))))
The problem is in the line of the "field". As default-value is null
"()", the field declaration gets:
(field -xxx ())
Then, the expansions sees this "()", and thinks it is an application of
no-function, getting the error:
#%app: missing procedure expression;
probably originally (), which is an illegal empty application in: (#%app)
So how could I specify some default value in that function so that the
field gets its default value as null? Using '() as default-value doesn't
work either, but however, if I generate exactly:
(field [,field-name null])
it works, so I'm expecting that more macro conversion steps are executed
to the unquote operator, but my knowledge doesn't go that far.
Thanks,
diego.
--
Diego Sevilla Ruiz -- http://ditec.um.es/~dsevilla/ -- dsevi...@um.es _.___
Dep. Ingeniería y Tecnología de Computadores, Facultad de Informática D|TEC
Univ.de Murcia,Campus Espinardo,30080 Murcia (SPAIN),Tel.+34868887571
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