In Emacs Speaks Statistics for R, how can the auto replacement of _ with <- be turned off?
To stop this smart behaviour, add (ess-toggle-underscore nil) to your .emacs after ess-site has been loaded.
What rcs said. But pressing _ again will turn the "<-" into "_" when you need it. So, when you need an underscore, just press it twice.
来源：https://stackoverflow.com/questions/1816238/how-to-turn-off-auto-replacement-in-emacs-speaks-statistics-for-r