+
+;;; BUG: The compiler will macroexpand the forms below (char str N)
+;;; will expand to internal SBCL code instead of our (setf char). It
+;;; is because macrodefinitions during bootstrapping are not included
+;;; in the host's environment. It should, but we have to think how to
+;;; avoid conflicts (package renaming??)
+
+;; (let ((str "hello"))
+;; (setf (char str 0) #\X)
+;; (setf (char str 4) #\X)
+;; (test (string= str "XellX")))