syntax-case oddity

[Francisco Solsona <solsona@acm.org>]

Hi all,

I was happily adding better error reporting to a very simple macro,
:optional, here's the final version:

(define-syntax (:optional stx)
	  (syntax-case stx ()
		       [(_ val default)
			(begin
			  (unless (list? (syntax val))
				  (raise-syntax-error #f "expected a list" stx (syntax val)))
			  (syntax (if (null? val) default (car val))))]))

but it hates the `(list? (syntax val))' thing:

> (:optional '(foo bar) 'foobar)
STDIN::3500: :optional: expected a list at: (quote (foo bar)) in: (:optional (quote (foo bar)) (quote foobar))

Am I missing something? BTW, the following do works:

(define-syntax (:optional stx)
	  (syntax-case stx ()
		       [(_ val default)
			(syntax (if (null? val) default (car val)))]))

> (:optional '(foo bar) 'foobar)
foo

poor error reporting, though:

> (:optional #f 'foobar)
car: expects argument of type <pair>; given #f

this is 200alpha9 (updated half an hour ago.)

Thanks,
--Francisco