R devel - Jul 2011 - R result objects as lists

Hello List,
I want to communicate between a minimalistc lisp that has
only numbers, symbols (also used as strings) and lists as datatypes, and R.

It should be no problem to send command strings from the lisp process
to the R childprocess.  

I know, R is mostly implemented in Scheme, and I read recently, that
these special return objects of R are really lists under the
hood. Therefore my questions:

1. When I send a command from a lisp (that iks not elisp) to an R
subprocess, how can I recieve the R result object as a list (and not a
special R object)?

2. Apart from graphics - are all R result objects lists (or numbers or
strings)? That is, is it safe to assume that the result of an R call
will always be either a number, a string or a list (under the hood)?

Cheers
Thorsten

On 26/07/2011 11:26 AM, Thorsten wrote:
> Hello List,
> I want to communicate between a minimalistc lisp that has
> only numbers, symbols (also used as strings) and lists as datatypes, and R.
>
> It should be no problem to send command strings from the lisp process
> to the R childprocess.
>
> I know, R is mostly implemented in Scheme,
No, the design of the original R interpreter was based on a Scheme 
interpreter, but it is mostly implemented in C.
>   and I read recently, that
> these special return objects of R are really lists under the
> hood. Therefore my questions:
>
> 1. When I send a command from a lisp (that iks not elisp) to an R
> subprocess, how can I recieve the R result object as a list (and not a
> special R object)?
>
> 2. Apart from graphics - are all R result objects lists (or numbers or
> strings)? That is, is it safe to assume that the result of an R call
> will always be either a number, a string or a list (under the hood)?
No, you need to treat the results as C structures under the hood.  Some 
are implemented as Lisp-like lists, but most are vectors with additional 
information about the type of object that is contained within (in a 
C-style array).

Duncan Murdoch

Duncan Murdoch <murdoch.duncan at gmail.com> writes:
> No, you need to treat the results as C structures under the hood.
> Some are implemented as Lisp-like lists, but most are vectors with
> additional information about the type of object that is contained
> within (in a C-style array).
That makes things a bit more complicated (for me).
Thanks for the info
Thorsten