Activating emacs-mode [Evil] in inferior-ess-mode fails

[gujiaxi]

I use Evil in most modes but I want to use its emacs-state in inferior-ess-mode. For this purpose, I add the following code in my .emacs file as usual:

(evil-set-initial-state 'inferior-ess-mode 'emacs)

Unfortunately, it doesn't work. It is still evil-state, i.e. vim style bindings, in inferior-ess-mode. Is evil invoked inside ESS? How can I enable Emacs state in ESS?

[dellison]

If you kill the inferior ESS buffer and restart it (after evaluating that code), is it still in normal state?

In my .emacs, I do it this way:

(let ((initial-state-emacs-modes '(...
                                   ess-help-mode
                                   inferior-ess-mode
                                   ...)))
  (mapc (lambda (m)
      (evil-set-initial-state m 'emacs))
    initial-state-emacs-modes))

...and that seems to work. But I seem to remember that it only appears to set the evil state you specify when a buffer in that mode is created, and not when you switch to one that already exists.

[gujiaxi]

If you kill the inferior ESS buffer and restart it (after evaluating that code), is it still in normal state?

Yes, it is still in normal state. As comparison, I can easily get into emacs state in inferior-python-mode using the similar method.

Steps to reproduce

1. In .emacs:

   ;; evil
   (require 'evil)
   (evil-mode t)
   (evil-set-initial-state 'inferior-ess-mode 'emacs)
   ;; ess
   (require 'ess)
   (add-to-list 'auto-mode-alist '("\\.[rR]\\'" . R-mode))

2. Run Emacs and do M-x R to start a inferior-ess-mode buffer.
3. It is in evil normal state instead of emacs state in this buffer.

[lionel-]

That's because ESS is not written in terms of proper modes. So the mode initialisation does not follow Emacs conventions because everything is done manually. In particular, after-change-major-mode-hook is not run.

There is a long-term plan to rewrite ESS with derived modes. We could add the proper run-hooks at the end of inferior-ess-mode though. Do you see any unintended side effects to this @vspinu?

In the meantime, one workaround for your problem is to add comint to the Emacs initial state. May I ask why you don't keep it in Evil state? With these hooked in inferior-ess-mode-hook, I personally think Evil is more usable:

 (setq-local comint-use-prompt-regexp nil)
 (setq-local inhibit-field-text-motion nil)

[gujiaxi]

@lionel- Thanks, comint way works like a charm.