how to turn this Gnus function into a macro?

[Ted Zlatanov <tzz@lifelogs.com>]

I tried to make this function into a macro but failed.  Any help will
be greatly appreciated.  As it is it works, so it's not a big deal but
I'm curious what I missed.  The Emacs docs on macros are pretty bad,
and my problem boiled down to being unable to (funcall) a macro by
name.

Thanks
Ted

(defun spam-fetch-field-fast (article field)
  "Fetch a field quickly, using the internal gnus-data-list function"
  (when (numberp article)
    (let* ((header (assoc article (gnus-data-list nil)))
	   (data-header (if header (gnus-data-header header) nil)))
      (cond
       ((equal field 'from)
	(mail-header-from data-header))
       ((equal field 'message-id)
	(mail-header-message-id data-header))
       ((equal field 'subject)
	(mail-header-subject data-header))
       ((equal field 'references)
	(mail-header-references data-header))
       ((equal field 'date)
	(mail-header-date data-header))
       ((equal field 'xref)
	(mail-header-xref data-header))
       ((equal field 'extra)
	(mail-header-extra data-header))
       (t
	nil)))))