init.el

;;----------------------------------------------------------------------------
;; Reason setup
;; Expects reason-cli to be installed:
;; npm install -g git://github.com/reasonml/reason-cli.git
;;----------------------------------------------------------------------------

(defun chomp-end (str)
  "Chomp tailing whitespace from STR."
  (replace-regexp-in-string (rx (* (any " \t\n")) eos)
                            ""
                            str))

(defun real-path (path)
  "Resolves the actual path for PATH."
  (chomp-end (shell-command-to-string (concat "realpath " path))))

(let ((support-base-dir (concat (replace-regexp-in-string "refmt\n" "" (shell-command-to-string (concat "realpath " (shell-command-to-string "which refmt")))) ".."))
      (merlin-base-dir (concat (replace-regexp-in-string "ocamlmerlin\n" "" (shell-command-to-string (concat "realpath " (shell-command-to-string "which ocamlmerlin")))) "..")))
  ;; Add npm merlin.el to the emacs load path and tell emacs where to find ocamlmerlin
  (add-to-list 'load-path (concat merlin-base-dir "/share/emacs/site-lisp/"))
  (setq merlin-command (concat merlin-base-dir "/bin/ocamlmerlin"))

  ;; Add npm reason-mode to the emacs load path and tell emacs where to find refmt
  (add-to-list 'load-path (concat support-base-dir "/share/emacs/site-lisp"))
  (setq refmt-command (concat support-base-dir "/bin/refmt")))

(require 'reason-mode)
(require 'merlin)
(add-hook 'reason-mode-hook (lambda ()
                              (add-hook 'before-save-hook 'refmt-before-save)
                              (merlin-mode)))

(setq merlin-ac-setup t)

(require 'merlin-iedit)
(defun evil-custom-merlin-iedit ()
  (interactive)
  (if iedit-mode (iedit-mode)
    (merlin-iedit-occurrences)))
(define-key merlin-mode-map (kbd "C-c C-e") 'evil-custom-merlin-iedit)