Less annoying way to switch input method when using evil-mode

sane-im-switch.el

;; prerequisites: im-select (https://github.com/daipeihust/im-select)
;;
;; install it!
;; $ curl -Ls https://raw.githubusercontent.com/daipeihust/im-select/master/install_mac.sh | sh
;; 
;; make sure that Emacs can execute 'im-select'. (Is it on the right $PATH?)


(setq english-im  "com.apple.keylayout.ABC")
(setq previous-im "com.apple.keylayout.ABC")

(defun use-english-im ()
   "use english input method"
  (interactive)
  (call-process-shell-command (concat "im-select " english-im)))

(defun set-previous-im ()
  "set input method to the previously saved one"
  (interactive)
  (setq previous-im
        (substring (shell-command-to-string "im-select") 0 -1)))

(defun use-previous-im ()
  "use the previous input method"
  (interactive)
  (call-process-shell-command (concat "im-select " previous-im)))
  

(add-hook 'evil-normal-state-entry-hook  'use-english-im)
(add-hook 'evil-insert-state-entry-hook  'use-previous-im)
(add-hook 'evil-insert-state-exit-hook   'set-previous-im)
(add-hook 'evil-replace-state-entry-hook 'use-previous-im)
(add-hook 'evil-replace-state-exit-hook  'set-previous-im)