Dear Jan, dear list,
This works fine in SWISH:
<- r = 1, R <- 0-r .
This raises an error (no R_expression)
<- r = 1, R <- -r .
Something similar is seen in rserve_client. I think the unary operators + and - are not translated to R. I think it is easily fixed, so, a few weeks ago I made a little pull request for rserve_client. It’s the first PR in my life, so I might have made something wrong and/or it might have been overlooked.