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

From: Stavros Macrakis <macrakis_at_alum.mit.edu>
Date: Tue, 10 Feb 2009 12:07:36 -0500

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.


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