>>>>> "hw" == hadley wickham <h.wick...@gmail.com>
>>>>> on Wed, 2 Sep 2009 14:02:06 -0500 writes:
hw> On Wed, Sep 2, 2009 at 1:54 PM, Stavros
hw> Macrakis<macra...@alum.mit.edu> wrote:
>> On Wed, Sep 2, 2009 at 2:39 PM, Stavros
>> Macrakis<macra...@alum.mit.edu> wrote:
>>
>>> Most types of language objects are regarded as
>>> recursive: those which are not are the atomic
>>> vector types, 'NULL' and symbols (as given by
>>> 'as.name').
>>>
>>> But is.recursive(as.name('foo')) ==
>>> is.recursive(quote(foo)) == FALSE.
>>
>> Sorry, this *is* consistent with the behavior. But if we
>> read "the atomic vector types, 'NULL' and symbols" as a
>> list of mutually exclusive categories, then
>> is.atomic(NULL)==FALSE is inconsistent.
hw> And the sentence could be more clearly written as:
hw> Most types of language objects are regarded as
hw> recursive, except for atomic vector types, 'NULL' and
hw> symbols (as given by 'as.name').
yes, that's a shorter and more elegant.
But before amending that, why
"language objects" instead of just "R objects" or "objects" ?
In the context of S and R when I'd hear "language objects",
I'd think of the results of
expression() , formula(), substitute(), quote()
i.e., objects for which is.language() was true.
So, I'm proposing
Most types of objects are regarded as recursive, except for
atomic vector types, \code{NULL} and symbols (as given by
\code{\link{as.name}}).
--
Martin Maechler
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