From Martin Maechler <maechler@stat.math.ethz.ch>  Mon Sep 28 13:34:58 1998
From: Martin Maechler <maechler@stat.math.ethz.ch> (Martin Maechler)
Date: Mon, 28 Sep 1998 14:34:58 +0200
Subject: 0.62.3 & pre0.63: different kinds of NULL objects..
Message-ID: <199809281234.OAA07721@sophie.ethz.ch>

Oh dear, this *is* quite a penible mess :

> N2 _ lapply(NULL, sum)
> N2
NULL
> is.null(N2)
[1] TRUE
> is.list(NULL)
[1] FALSE
> is.list(N2)
[1] TRUE

---- i.e.,  N2  is ``almost'' like NULL but not quite !

---- I found the bug in a version of the following:

> array(1:6, dim=3:1, dimnames=NULL)
, , 1

     [,1] [,2]
[1,]    1    4
[2,]    2    5
[3,]    3    6

> array(1:6, dim=3:1, dimnames=N2)
Error: length of dimnames must match that of dims

---------------
Martin Maechler <maechler@stat.math.ethz.ch>	http://stat.ethz.ch/~maechler/
Seminar fuer Statistik, ETH-Zentrum SOL G1;	Sonneggstr.33
ETH (Federal Inst. Technology)	8092 Zurich	SWITZERLAND
phone: x-41-1-632-3408		fax: ...-1086			<><
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0.62.3 & pre0.63: different kinds of NULL objects..
Martin Maechler