Setup environment variables using opam

   #+BEGIN_SRC emacs-lisp :tangle no
(dolist (var (car (read-from-string (shell-command-to-string "opam config env --sexp"))))
  (setenv (car var) (cadr var)))
   #+END_SRC

   Add opam libs.

   #+BEGIN_SRC emacs-lisp
(let ((opam-share (ignore-errors (car (process-lines "opam" "config" "var" "share")))))
  (when (and opam-share (file-directory-p opam-share))
    (add-to-list 'load-path (expand-file-name "emacs/site-lisp" opam-share))
    ))
   #+END_SRC

   Install caml, reasonml and tuareg modes.

   We don't need the tuareg package from the emacs repositories, it
   comes from opam.

   ~caml~ is required because ~caml-types-expr-face~ is used by merlin.

   #+BEGIN_SRC emacs-lisp
(use-package caml
  :ensure t)
(use-package tuareg
  :mode ("\\.ml[ily]?$" . tuareg-mode))
(use-package reason-mode
  :ensure t)
   #+END_SRC

   Require ocp stuff first because of conflicts between shortcuts.
   It is installed from opam, ~ensure~ is not required.

   #+BEGIN_SRC emacs-lisp
(use-package ocp-indent)
(use-package ocp-index)
   #+END_SRC

   Configure merlin. Magical autocompletion and IDE features.

   #+BEGIN_SRC emacs-lisp
(use-package merlin
  :custom
  (merlin-command 'opam)
  (merlin-completion-with-doc t)
  (company-quickhelp-mode t)
  :bind (:map merlin-mode-map
              ("M-." . merlin-locate)
              ("M-," . merlin-pop-stack)
              ("C-c C-o" . merlin-occurrences)
              ("C-c C-j" . merlin-jump)
              ("C-c i" . merlin-locate-ident)
              ("C-c C-e" . merlin-iedit-occurrences)
              )
  :hook
  ;; Start merlin on ml files
  (reason-mode . merlin-mode)
  (tuareg-mode . merlin-mode)
  (caml-mode-hook . merlin-mode)
  )
   #+END_SRC

   #+BEGIN_SRC emacs-lisp
(use-package utop
  :hook
  (tuareg-mode . utop-minor-mode)
  (reason-mode . utop-minor-mode)
  )
   #+END_SRC