XOR

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

    Date:     Sun, 22 Dec 85 17:15 EST
    From:     MURRAY%umass-cs.csnet@CSNET-RELAY.ARPA

      I think the discussion about whether there should be an XOR
    function is very much off the mark.  I think the criterion for
    including any new  operator in the language should be one of
    the following: 
      1) It is not possible to write it in Common Lisp.
      2) It can be implemented MUCH more
	 efficiently in an implemention dependant way.
      3) It requires a lot of programming effort (and is generally useful).

    As long as an operator is implementable in Common Lisp, your program
    would still be portable.
    The only problem that could arise is that your function/macro
    is called something that later on becomes defined in Common Lisp, with
    different syntax/semantics.  But that problem exists with ANY operator
    that you define, and packages can deal with it.  Thus I see no reason
    to include something like XOR.  The language is certainly big enough
    already.  

I agree completely.  I could not have stated my position as clearly and
completely as you have.

LATER: I also agree with the other people who said that a 4th criterion
should be added, that enough people will use it that it's important to
standardize the name, even though everyone could implement it for themselves.
They seemed to think that by saying this they were disagreeing with you,
but I didn't read what you said as disagreeing with that sentiment.

[Rest of message, about other issues, not included in this particular reply]