open-stream-p (ANSI and GNU Common Lisp Document)

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#### 21.2.11 open-stream-p [Function]

`open-stream-p` stream ⇒ generalized-boolean

#### Arguments and Values::

stream—a stream.

generalized-boolean—a generalized boolean.

#### Description::

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

Streams are open until they have been explicitly closed with close, or until they are implicitly closed due to exit from a with-output-to-string, with-open-file, with-input-from-string, or with-open-stream form.

#### Examples::

     (open-stream-p *standard-input*) ⇒  true

#### Affected By::

close.

#### Exceptional Situations::

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