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21.2.12 stream-element-type [Function]

stream-element-type stream => typespec

Arguments and Values::

stream—a stream.

typespec—a type specifier.

Description::

stream-element-type returns a type specifier that indicates the types of objects that may be read from or written to stream.

Streams created by open have an element type restricted to integer or a subtype of type character.

Examples::
     ;; Note that the stream must accomodate at least the specified type,
     ;; but might accomodate other types.  Further note that even if it does
     ;; accomodate exactly the specified type, the type might be specified in
     ;; any of several ways.
      (with-open-file (s "test" :element-type '(integer 0 1)
                                :if-exists :error
                                :direction :output)
        (stream-element-type s))
     =>  INTEGER
     OR=> (UNSIGNED-BYTE 16)
     OR=> (UNSIGNED-BYTE 8)
     OR=> BIT
     OR=> (UNSIGNED-BYTE 1)
     OR=> (INTEGER 0 1)
     OR=> (INTEGER 0 (2))
Exceptional Situations::

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