nconc semantics

[pap@unagi.cis.upenn.edu]

What a surprise when we ran into this:

-> (mapcan #'(lambda(x) t) '(1 2 3))
-> NIL
-> (nconc t nil)
-> NIL
-> (nconc t)
-> NIL

The definition of nconc is:

(DEFUN NCONC (&REST ARG)
	(COND ((NULL ARG) NIL)
	      ((NULL (CDR ARG)) (CAR ARG))
	      (T (*NCONC1 ARG))))

Should'nt nconc test for taking lists (and nothing else) as arguments?

Could you please reply to :

	 pap@linc.cis.upenn.edu
and to	 schabes@linc.cis.upenn.edu


Thanks a bunch for your help.