Issue: STREAM-ELEMENT-TYPE-EXAMPLES

[ROSENKING@A.ISI.EDU]

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Status:	Initial Proposal
Issue:			STREAM-ELEMENT-TYPE-EXAMPLES
References:		STREAM-ELEMENT=TYPE (CLtL, page 332, ANSI Draft, 
								page 6-38)
Category:		CLARIFICATION
Edit History:		26 -Oct-88, Version 1 by Rosenking

Related Issues:

Problem Description:

Below is a list of the examples and specified outputs which are used in the
ANSI draft standard.

(stream-element-type *debug-io*)   --->   STRING-CHAR
(stream-element-type (make-concatenated-stream))   -->   T
(setq s (open "tempfile.temp"
		:element-type 'bit
		:if-does-not-exist :create))   -->   <stream identifier>
(stream-element-type s)   -->   (INTEGER 0 1)

The following describes the inconsistencies with the above examples.  
The first expression returns the value STRING-CHAR when executed on the Mac, 
but when executed on the Symbolics it returns the value CHARACTER (Note: 
STRING-CHAR is a subtype of CHARACTER). 

The second expression returns the value T when executed on the Symbolics, 
though it returns the value STRING-CHAR when executed on the Mac, and it then
 returns the value NIL when executed on the VAX.

The third expression does not evaluate correctly on the Symbolics and VAX
implementations where the :direction keyword default value is :input, though
it does evaluate correctly on the MAC implementation where the default value
for :direction is :output.

The fourth expression also returns different values. On the MAC and VAX
implementations the value BIT is returned for this expression, while
Symbolics returns the value (UNSIGNED-BYTE 16). The :direction :output 
specification had to be made to the third expression in order for the VAX
and Symbolics implementations to evaluate the last expression.

Proposal:

Clarify what the appropriate outputs for each of these expressions should be
over all implementations.

Rationale:

For validity and conformance.

Current Practice:

As stated in problem description for each expression and implementation.

Adoption Cost:

Benefits:

Standardization and portability.

Conversion Cost:

Aesthetics:

Discussion: