Hello Guys,
Following up my earlier mail where I am trying to write an alternative
front-end for R, I had a question about accessing the closures and
environments in R code.
Here's the function taken and modified a little from "*Lexical Scope and
Statistical Computing*"
=====================================================================
f<-function(){
Rmlfun<-function(x){
sumx <- sum(x)
n <- length(x)
function(mu)
n*log(mu)-mu*sumx
}
efun <-Rmlfun(1:10)
y1 <- efun(3)
print(y1)
efun2 <- Rmlfun(20:30)
y2 <- efun2(3)
print(y2)
}
=====================================================================
Now assignment efun <-Rmlfun(1:10) creates a closure where
*function(mu) n*log(mu)-mu*sumx *is returned and *sumx* and *n *are added
to the existing environment.
I can parse the code using *PROTECT(e =
R_ParseVector(tmp,1,&status,R_NilValue));* where tmp is the buffer
containing the same source. I can walk the resultant parser output and
build and alternative Abstract syntax tree(AST).
I would like to include the information about closure/environments in my
AST so that I can possibly do some optimizations.
My question is, how can I get hold of this information?
One thing I noticed while 'walking' through the parser output, I never
encounter a CLOSXP (which I check using TYPEOF()) , even though in the
above code, closure is created. Is it the case that this information is
meant just for the internal "eval*" function and not exposed application
writers?
Thanks,
Rob
[[alternative HTML version deleted]]
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
