input-stream—an input stream designator. The default is standard input.
Clears any available input from input-stream.
clear-input does not make sense for input-stream,
clear-input does nothing.
;; The exact I/O behavior of this example might vary from implementation ;; to implementation depending on the kind of interactive buffering that ;; occurs. (The call to SLEEP here is intended to help even out the ;; differences in implementations which do not do line-at-a-time buffering.) (defun read-sleepily (&optional (clear-p nil) (zzz 0)) (list (progn (print '>) (read)) ;; Note that input typed within the first ZZZ seconds ;; will be discarded. (progn (print '>) (if zzz (sleep zzz)) (print '>>) (if clear-p (clear-input)) (read)))) (read-sleepily) ▷ > 10 ▷ > ▷ >> 20 → (10 20) (read-sleepily t) ▷ > 10 ▷ > ▷ >> 20 → (10 20) (read-sleepily t 10) ▷ > 10 ▷ > 20 ; Some implementations won't echo typeahead here. ▷ >> 30 → (10 30)
The input-stream is modified.
Should signal an error of type
type-error if input-stream is not a stream designator.