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Re: Of growing code and diminishing hacks...

    (define (overloaded-cdr val)
    	(if (null? val) nil (cdr val)))
    (overloaded-cdr (assq key a-list))
    	In other words, if you want a cdr that horribly overloads nil, then
    write one.  As for me, I think of a cons cell as an object with car and
    cdr fields in it, just as a point is an object with x and y fields in
    it.  How about:
    (define (overloaded-x point)
    	(if (null? point) nil (x point)))
So  now  we  have a proliferation of functions.  You could just as well think
of CAR and CDR as operations, and NIL as  an  object  that  handles  them  by
returning  NIL.  Much cleaner.  Well, maybe not; I guess that's debatable.  I
think the code is cleaner even though the semantics that  the  compiler  must
implement  may  become  a  little hairier.  But that's what compilers are for