;; the "latest" code always picks the 32-bit version.  This hack
;; finds the latest 64-bit version.
(defun R64 (&optional start-args)
  "Call the latest 64-bit version of R"
  (interactive "P")
  ;; sweep through the list of R-version commands
  ;; to find the 64-bit ones
  (defun m64 (target)
    "remove string '-64bit' from target"
    (if (string-match "-64bit" target)
	(replace-match "" t t target)
      ))
   (setq nobits(delq nil (mapcar 'm64 ess-r-versions-created)))
   ;; now use the newest version that matches a 64-bit version
   (defun krc-in-newest (source)
     (if source 
	 (if (string-match source ess-newest-R)
	     (concat source "-64bit")
	   nil)
       nil))
   (setq pending (delq nil (mapcar 'krc-in-newest nobits)))
   ;; take the first one
   (setq myname (car pending))
   ;; convert from string to symbol
   (setq mysym (intern-soft myname))
   ;; look up the function from the symbol
   (setq myfun (symbol-function mysym))
   ;; invoke it
   (funcall myfun start-args)
)