S Compatibility (Was: Re: R-beta: 'all.names' function -- failing as.list( _function_ ))

[Ross Ihaka]

Peter Dalgaard writes:

> Ross Ihaka <ihaka at stat.auckland.ac.nz> writes:

> > Many of the incompatibilities result from us not being familiar with
> > some of the inner mysteries of S - these are generally pretty easy to
> > fix.  Some incompatibilities however result from the fact that R
> > started life as a kind of Lisp interpreter.  These can be quite a bit
> > harder to fix.

> Also (this is an absolutely uninformative and uninformed remark, I
> know) I hope you/we will think these matters over very carefully,
> before possibly throwing a baby out with the bathing water. Some of
> the mysteries of S are probably better categorized as design bugs, and
> in contrast Lisp-dialects have been subjected to a long history of
> analysis by computer scientists in all the critical issues of memory
> handling, scoping rules, optimizability, compilability, etc.

> A little divergence between the two languages is not really critical,
> we already have it in the scoping rules, and as long as the internal
> logic is OK, I don't think that the porting issues are all that bad.

The primary reason for having S compatibility is so that we "buy" (some
might say "steal") applications [and I must say I am both surprised and
gratified at the number which seem to be appearing - thanks to everyone
for this!].

For the most part, the "price" of compatibility is small and in a
number of cases moving from our own (sometimes confused) model to the S
one has been a big win.

Some things we almost certainly won't be changing.  Scoping is one of
these (although I have to confess that I have made the pitch to Robert
that we should drop our scoping in favour of the S version - he
sensibly said "no").

It's very important that there be a "free" alternative to to S-PLUS
(I have just deleted a long tirade about this - you're probably all
converts anyway).  ``Giving in'' on a few points is a small price to
pay for enough applications to ensure R's success.

	Ross
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