LispWorks User Guide and Reference Manual > 22 Internationalization > 22.6 External Formats and File Streams

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22.6.4 External formats and stream-element-type

The :element-type argument in open and with-open-file defaults to the value of *default-character-element-type*.

If element-type is not :default , checks are made to ensure that the resulting stream's stream-element-type is compatible with its external format:

  1. If direction is :input or :io , the element-type argument must be a supertype of the type of characters produced by the external format.
  2. If direction is :output or :io , the element-type argument must be a subtype of the type of characters accepted by the external format

If the element-type argument doesn't satisfy these requirements, an error is signalled.

If element-type is :default the system chooses the stream-element-type on the basis of the external format.


LispWorks User Guide and Reference Manual - 22 Dec 2009

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