Issue: RETURN-VALUES-UNSPECIFIED (Version 5)

[masinter.pa@Xerox.COM]

said CLOSE returns T, pointed out that REQUIRE and PROVIDE
might go away.

!
Issue:        RETURN-VALUES-UNSPECIFIED
References:   CLOSE (p 332), IN-PACKAGE (p 183), RENAME-PACKAGE (p 184),
	      TRACE (p 440), UNTRACE (p 440), INSPECT (p 442), 
	      SET-SYNTAX-FROM-CHAR (p 361),
	      LOCALLY (p 156), PROVIDE (p 188), REQUIRE (P 188)
Related issues: REQUIRE-PATHNAME-DEFAULTS
Category:     CLARIFICATION
Edit history: 26-Aug-88, Version 1 by Chapman
	      19-Sept-88, Version 2 by Chapman
		 6-Oct-88, Version 3 by Masinter
		 7-Oct-88, Version 4 by Masinter
		26-Nov-88, Version 5 by Masinter
 
Problem Description:
 
The descriptions of CLOSE, IN-PACKAGE, RENAME-PACKAGE, TRACE, UNTRACE,
INSPECT, SET-SYNTAX-FROM-CHAR, LOCALLY, PROVIDE, and REQUIRE 
are not clear about the values returned from those constructs.
 
Proposal (RETURN-VALUES-UNSPECIFIED:SPECIFY)
 
Clarify that the return values for the listed constructs are as follows:
 
CLOSE -- T
IN-PACKAGE -- the new package, i.e. the value of *PACKAGE* after the
execution of IN-PACKAGE.
RENAME-PACKAGE -- the renamed package.
TRACE (when called with arguments) -- implementation-dependent.
UNTRACE -- implementation-dependent.
INSPECT -- implementation-dependent.
SET-SYNTAX-FROM-CHAR -- T
LOCALLY -- the return values of the last form of its body, i.e. the body is
	surrounded by an implicit PROGN.
PROVIDE -- implementation-dependent.
REQUIRE -- implementation-dependent.
 
Rationale:
 
This clarification allows users to know when they can and can not
count on the values returned from these constructs. 
 
Current Practice:

Varies; the choices made here are consistent with many but
not all implementations.
  
Cost to Implementors:
 
Small.

Benefits:
 
This clarification will assist users in writing portable code.
 
Cost to users:
 
Small; it seems unlikely that there is much code that currently
depends on the return values of these functions; such code isn't
portable.

Aesthetics:
 
Specified is better than not, when it makes sense.
 
Discussion:
 
PROVIDE and REQUIRE are not likely to appear except in the "top level" of
files, and so their return value is possibly moot.  Another proposal would
eliminate them from the language, and then their return value would definitely
be moot!

There is some sentiment for leaving unspecified the values of the
debugging/environment features such as TRACE and UNTRACE,
for the same reasons that so much else of their behavior is unspecified.