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21.2.9 input-stream-p, output-stream-p [Function]

input-stream-p stream => generalized-boolean

output-stream-p stream => generalized-boolean

Arguments and Values::

stream—a stream.

generalized-boolean—a generalized boolean.

Description::

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.

Examples::
      (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
Exceptional Situations::

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