I Wasted Time with a Custom Prompt for R with ESS

I wanted a custom prompt for R with ESS. I wanted a double struck R. I probably did it wrong. It never worked. Actually it worked most of the time, and that is worse than never working. Kind people helped me. I still got it wrong. I take full responsibility. It was better not to do it. If you want to try, here is where I left it.

.Rprofile

Make the ℝ prompt stand out (be sure to tell ESS how to handle this):

options(prompt="ℝ> ")

.emacs.el

Tell ESS how to handle my custom prompt:

(setq inferior-ess-primary-prompt "ℝ> ")

Handle the custom ℝ prompt in ess. Don’t use custom here.

(setq inferior-S-prompt "[]a-zA-Z0-9.[]*\\(?:[>+.] \\)*ℝ+> ")