MULTPLE-VALUE-OR &rest args

[David A. Moon <Moon@STONY-BROOK.SCRC.Symbolics.COM>]

    Date:     Tue, 21 Apr 87 15:45 EDT
    From:     MURRAY%cs.umass.edu@RELAY.CS.NET

     >I don't think this conclusion follows from your previous paragraph.
     >If the proposed MULTIPLE-VALUE-OR can easily be implemented in terms of
     >existing primitives, such as MULTIPLE-VALUE-CALL, and would be efficient
     >if there were non-consing &rest arguments, and non-consing &rest arguments
     >are desirable for other reasons, then I think a more logical conclusion is
     >"because non-consing &rest arguments can only be done efficiently by low-level
     >implementation-specific code, they should be in Common Lisp."

    Are you just pointing out a flaw in my logic, or are you suggesting that
    Common Lisp REQUIRE certain &rest args to not cons?  

I was suggesting that a declaration which, like all declarations,
encourages but does not require the compiler to generate a certain kind
of code, could be added to Common Lisp.  If it were added, it would be
more broadly applicable than MULTIPLE-VALUE-OR, and would eliminate the
need for MULTIPLE-VALUE-OR as a special language construct since it
would make the portable definition of MULTIPLE-VALUE-OR efficient.

							 The last sentence
    was not meant to logically follow from the previous -- I was merely
    re-iterating my point in requesting a MULTIPLE-VALUE-OR form, which is it
    can be efficiently implemented WITHOUT non-consing rest args.  I might
    also add that using MULTIPLE-VALUE-CALL is going to require both 
    a Lambda and a Block, in which the Return-From will end up being a Throw.

You are assuming that (multiple-value-call #'(lambda ...) ...) cannot be compiled
as efficiently as ((lambda ...) ...).  I see no justification for assuming that.