ct:defctype within (LET

I'm getting an error when I try create a ctype within a call to LET, 
or even pre-LET (but still within the scope of SET-COLORS).

(defun set-colors ()
    (let (
            (colors (make-hash-table)))
        (ct:defctype colour-arrayu (GLubyte 4))
        (mapcar #'(lambda (x)
                (setf (gethash x colors)
                    (ct:malloc (ct:sizeof 'colour-arrayu))))
            '(white red green blue yellow black orange purple))

    (values colors)))

;;; An error occurred in function MACROEXPAND:
;;; Error: Invalid C type specifier: COLOUR-ARRAYU

... There is no error when (ct:defctype colour-arrayu (GLubyte 4)) 
is called at the top level.


------------------------ Yahoo! Groups Sponsor ---------------------~-->
Get 128 Bit SSL Encryption!
http://us.click.yahoo.com/xaxhjB/hdqFAA/xGHJAA/SyjtlB/TM
---------------------------------------------------------------------~->

To unsubscribe from this group, send an email to:
cormanlisp-unsubscribe@xxxxxxxxxxxxxxx

 

Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/