The facility for defining and calling R functions in gretl has now been extended to support strings on input and output. (Previously this worked only for scalars and matrices). This is in git, and will be in the 2018a release. Trivial example follows: <hansl> set R_functions on foreign language=R strfun <- function(s) { s <- paste(s, "blossom") } end foreign string s = R.strfun("cherry") print s </hansl> Allin