;;; Succeeds in Clasp and SBCL.
(uiop:with-output-file (s #P"/tmp/blah.txt" :element-type :default :if-exists :supersede)
  (write-byte 1 s)
  (write-char #\a s))
;;; Succeeds in Clasp, fails in SBCL.
(uiop:with-output-file (s #P"/tmp/blah.txt" :element-type '(unsigned-byte 8) :if-exists :supersede)
  (write-byte 1 s)
  (write-char #\a s))
;;; Succeeds in Clasp, fails in SBCL.
(uiop:with-output-file (s #P"/tmp/blah.txt" :element-type 'character :if-exists :supersede)
  (write-byte 1 s)
  (write-char #\a s))

;;; Fails in Clasp, succeeds in SBCL.
(uiop:with-input-file (s #P"/tmp/blah.txt" :element-type :default)
  (format t "~A ~A~%" (read-byte s) (read-char s)))
;;; Succeeds in Clasp, fails in SBCL.
(uiop:with-input-file (s #P"/tmp/blah.txt" :element-type '(unsigned-byte 8))
  (format t "~A ~A~%" (read-byte s) (read-char s)))
;;; Fails in Clasp, fails in SBCL.
(uiop:with-input-file (s #P"/tmp/blah.txt" :element-type 'character)
  (format t "~A ~A~%" (read-byte s) (read-char s)))