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interactive-stream-p

interactive-stream-p Function

Syntax:

interactive-stream-p stream → generalized-boolean

Arguments and Values:

stream—a stream.

generalized-boolean—a generalized boolean.

Description:

Returns true if stream is an interactive stream; otherwise, returns false.

Examples:

(when (> measured limit) 
  (let ((error (round (\* (- measured limit) 100) 
		      limit))) 
    (unless (if (interactive-stream-p \*query-io\*) 
		(yes-or-no-p "The frammis is out of tolerance by ~D%.~@ 
Is it safe to proceed? " error) 
		(< error 15)) ;15% is acceptable 
      (error "The frammis is out of tolerance by ~D%." error))))

Exceptional Situations:

Should signal an error of type type-error if stream is not a stream.

See Also:

Section 21.1 (Stream Concepts)

Expanded Reference: interactive-stream-p​

Basic Usage​

interactive-stream-p returns true if the stream is interactive (e.g., a terminal), false otherwise.

;; String streams are not interactive
(interactive-stream-p (make-string-input-stream "test"))
=> NIL

String Output Stream​

(interactive-stream-p (make-string-output-stream))
=> NIL

Conditional Behavior Based on Interactivity​

A common use is to vary behavior depending on whether the user is present at a terminal.

;; Example pattern (not runnable as-is since it depends on the environment)
;; (if (interactive-stream-p *query-io*)
;;     (yes-or-no-p "Proceed?")
;;     t)  ; auto-accept in non-interactive mode

Standard Streams​

The result for *standard-input* or *terminal-io* depends on the implementation and the environment.

;; In a REPL session, these would typically return T:
;; (interactive-stream-p *standard-input*) -> T
;; In a batch/script environment, they might return NIL.