Auto complete is good, it can save you times in typing and prevent typo sometimes.

RStudio now supports function arguments in auto complete. ESS’s auto complete is more advance, it supports help page.

We should use ‘ess-use-auto-complete’ to activate auto complete in ESS buffers.

(setq ess-use-auto-complete t)

The effect is quite amazing.

Auto-complete extension is needed for ESS, we need to install the auto-complete extension and load it at Emacs startup.

(require 'auto-complete)
(require 'auto-complete-config)
(add-to-list 'ac-dictionary-directories "~/.emacs.d/site-lisp/auto-complete/dict")
(ac-config-default)
(auto-complete-mode)