input-stream-p stream → generalized-boolean

output-stream-p stream → generalized-boolean

stream — a stream.

generalized-boolean — a generalized boolean.

input-stream-p returns true if stream is an input stream; otherwise, returns false.

output-stream-p returns true if stream is an output stream; otherwise, returns false.

(input-stream-p *standard-input*) → true 
(input-stream-p *terminal-io*) → true 
(input-stream-p (make-string-output-stream)) → false 

(output-stream-p *standard-output*) → true 
(output-stream-p *terminal-io*) → true 
(output-stream-p (make-string-input-stream "jr")) → false

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