R devel - Sep 2008 - lapply(NULL, ...) returns empty list

Dear R-devel,

Is there a reason that lapply(NULL, ...) returns the empty list, rather than
NULL? It seems intuitive to expect the latter, and rather counterintuitive that
lapply(list(), ... ) returns the same value as lapply(NULL, ...).
> lapply(list(), function(x) 1)
list()
>  lapply(NULL, function(x) 1)
list()
> version
               _
platform       i386-pc-mingw32
arch           i386
os             mingw32
system         i386, mingw32
status
major          2
minor          7.1
year           2008
month          06
day            23
svn rev        45970
language       R
version.string R version 2.7.1 (2008-06-23)
>
Regards,
Vadim

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On Thu, Sep 4, 2008 at 4:01 PM, Vadim Organovich
<vogranovich at jumptrading.com> wrote:
> Dear R-devel,
>
> Is there a reason that lapply(NULL, ...) returns the empty list, rather
than NULL? It seems intuitive to expect the latter, and rather counterintuitive
that lapply(list(), ... ) returns the same value as lapply(NULL, ...).

  X: a vector (atomic or list) or an expressions vector.  Other
          objects (including classed objects) will be coerced by
          'as.list'.
> as.list(NULL)
list()

Hadley

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