I have spacemacs and when I edit a .py or .c file line numbering is turned on no problem, however when I open a .R file it isn't there (the mode is named ESS[S] to be precise). How can I turn it on here too ?
You have to turn linum-mode on after starting ess-mode. This mode takes care of adding line numbers.
(add-hook 'ess-mode-hook 'linum-mode)
