[R] R and Scheme

[Wacek Kusnierczyk]

Stavros Macrakis wrote:
> There is no equivalent to set-car!/rplaca (not even pairlists and
> expressions).  For example, r<-pairlist(1,2); r[[1]]<-r does not create a
> circular list. And in general there doesn't seem to be substructure sharing
> at the semantic level (though there may be in the implementation).
>
>   

again, you can achieve the effect with environments:

e = new.env(parent=emptyenv())
e$e = e
e
e$e$e$e


vQ