Access R from SWI-Prolog

1. Please start R and install the two packages Rcpp and RInside. R> install.packages('Rcpp', 'RInside')
2. Please start SWI-Prolog and then install the pack rologpp SWI> assert(prolog_pack:environment('R_LIBS_USER', X) :- getenv('R_LIBS_USER', X)). (This is needed if you installed the R packages in a local "user" directory)

   SWI> pack_install(rologp). (Please note that rologp is written with only one p)

   SWI> use_module(library(rologp)).

   SWI> r_eval(2+2, X).