ocaml: use utop and ocp-indent plugins

utop as REPL
ocp-indent for indentation

contrib/lang/ocaml/packages.el

@@ -14,6 +14,8 @@
   '(
     tuareg
     merlin
+    utop
+    ocp-indent
 ;;    flycheck
 ;;    flycheck-ocaml
     ;; package ocamls go here
@@ -23,8 +25,36 @@
   (add-hook 'tuareg-mode-hook #'merlin-mode)
   )
 
-(defun ocaml/init-merlin ())
+(defun ocaml/opam ()
+  (setq opam-share (substring (shell-command-to-string "opam config var share 2> /dev/null") 0 -1))
+  (setq opam-load-path (concat opam-share "/emacs/site-lisp"))
+  (add-to-list 'load-path opam-load-path))
 
+(defun ocaml/init-utop ()
+  (use-package utop
+    :init
+    (autoload 'utop "utop" "Toplevel for OCaml" t)
+    (autoload 'utop-minor-mode "utop" "Minor mode for utop" t)
+    (add-hook 'tuareg-mode-hook 'utop-minor-mode)
+    :config
+    ;; Setup environment variables using opam
+    (dolist (var (car (read-from-string (shell-command-to-string "opam config env --sexp"))))
+      (setenv (car var) (cadr var)))
+    ;; Update the emacs path
+    (setq exec-path (append (parse-colon-path (getenv "PATH"))
+                            (list exec-directory)))
+    )
+  )
+
+(defun ocaml/init-ocp-indent ()
+  (use-package ocp-indent
+    :defer t
+    :init
+    (ocaml/opam)
+    )
+  )
+
+(defun ocaml/init-merlin ())
 ;; (defun ocaml/init-flycheck-ocaml ()
 ;;   (progn
 ;;     (setq merlin-error-after-save nil)