Sane switching of input methods when using evil-mode in Emacs on OSX

switch.el

;; switch to english input method when switching to normal mode
;; and switch back when entering insert/replace modes
;; need external script support, currently mac-only
(defvar default-im "com.apple.keylayout.Dvorak" "Default ascii-only input method")
(defvar prev-im (substring (shell-command-to-string "~/bin/im-select") 0 -1) 
 "IM that I use when starting Emacs and exiting insert mode")

(defun im-use-dvorak ()
  "Switch to Dvorak input method on a Mac. im-select is a tool 
provided at http://git.io/ndA8Mw"
  (interactive)
  (cond ((eq system-type 'darwin)
	 (call-process-shell-command (concat "~/bin/im-select " default-im)))))

(defun im-remember ()
  "Remember the input method being used in insert mode, 
so we can switch to it in other modes."
  (interactive)
  (cond ((eq system-type 'darwin)
	 (setq prev-im (substring (shell-command-to-string "~/bin/im-select") 0 -1)))))

(defun im-use-prev ()
  "Use previous input method. 
If previous input method is not defined, use default method"
  (interactive)
  (cond ((eq system-type 'darwin)
	 (if prev-im
	     (call-process-shell-command (concat "~/bin/im-select " prev-im))
	   (call-process-shell-command (concat "~/bin/im-select " default-im))))))

(add-hook 'evil-normal-state-entry-hook 'im-use-dvorak)
(add-hook 'evil-insert-state-entry-hook 'im-use-prev)
(add-hook 'evil-insert-state-exit-hook 'im-remember)
(add-hook 'evil-replace-state-entry-hook 'im-use-prev)
(add-hook 'evil-replace-state-exit-hook 'im-remember)
(add-hook 'evil-emacs-state-entry-hook 'im-use-dvorak)

Easy to adapt to a linux system (e.g. with xkb-switch). Works perfectly!