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defvar, defparameter, :unbound



    From: Daniel L. Weinreb <DLW@SCRC-QUABBIN.ARPA>
        Date: Sat, 2 Nov 85 23:55:45 EST
        From: Nick Papadakis <isrlist@tove.umd.edu>

        On the lispmachines, defvar will take a second argument of :unbound,
        meaning that the variable will be initialized to an unbound state.

    I'm not sure which Lisp machine this message is supposed to apply to,
    but just for the record, the Symbolics system does not do this.

This hack was added to NIL.  My personal feeling is that the special
case value is just asking to screw some poor user whose code just
happens to naively use :UNBOUND to mean something...   But i added the
defvar hack anyway, because the ability to do both the defvar and
specify the documentations string in a single form seemed worth it.
Doing
	(defvar *foo*)
	(setf (documentation '*foo* 'variable) "Documentaiton string")
looks pretty crufty.  Keyworded defvar, anyone?