From macrakis at alum.mit.edu  Tue Feb 10 18:07:36 2009
From: macrakis at alum.mit.edu (Stavros Macrakis)
Date: Tue, 10 Feb 2009 12:07:36 -0500
Subject: [Rd] Variable/function namespaces WAS: Bug in subsetting data frame
	(PR#13515)
Message-ID: <8b356f880902100907s7f21cd65vf57043f134273b20@mail.gmail.com>

On Tue, Feb 10, 2009 at 10:11 AM, Duncan Murdoch <murdoch at stats.uwo.ca> wrote:
> Stavros Macrakis wrote:
>> On Tue, Feb 10, 2009 at 8:31 AM, Duncan Murdoch <murdoch at stats.uwo.ca>wrote:
>>> The evaluator recognizes the context of usage and will get the
>>> function for a function call....
>> Can you point me to chapter and verse in the language definition...
> No, I'm also unable to find it.

! This seems like a pretty fundamental thing to leave undocumented....

> ...I think originally there was no difference, and it caused the obvious trouble when people used variable names like t and c other short function names, so this was added.  I don't remember whether the different lookup rules showed up first in R or S.

There is an interesting discussion of these issues (in a Lisp context)
in "Technical Issues of Separation in Function Cells and Value Cells"
Lisp and Symbolic Computation 1:1:81 (6/1988) -- available at
http://www.nhplace.com/kent/Papers/Technical-Issues.html.  I don't
think an R-style approach is discussed there, though.

                -s



[Rd] Variable/function namespaces WAS: Bug in subsetting data frame (PR#13515)
Stavros Macrakis