Improve ocaml language support

See README.org.

Signed-off-by: Edwin Török <edwin@etorok.net>

modules/lang/ocaml/config.el

@@ -1,13 +1,83 @@
 ;;; lang/ocaml/config.el -*- lexical-binding: t; -*-
 
-(def-package! tuareg
-  :mode ("\\.ml[4ilpy]?\\'" . tuareg-mode))
+;; def-project-mode!/associate! doesn't work when a
+;; package is lazy loaded, and everything is compiled
 
+(def-package! tuareg
+  :defer t ;; modes set by autoload
+  :config
+  ;; tuareg-mode has the prettify symbols itself
+  (set-pretty-symbols! 'tuareg-mode :alist
+    (append tuareg-prettify-symbols-basic-alist
+            tuareg-prettify-symbols-extra-alist))
+  (setq tuareg-prettify-symbols-full t)
+  ;; Use opam to set environment
+  (setq tuareg-opam-insinuate t)
+  (tuareg-opam-update-env (tuareg-opam-current-compiler))
+  ;; Spell-check comments
+  (when (featurep! :feature spellcheck)
+    (add-hook 'tuareg-mode-hook #'flyspell-prog-mode)))
 
 (def-package! merlin
   :after tuareg
-  :hook (tuareg-mode . merlin-mode)
+  :init
+  (set-lookup-handlers! 'tuareg-mode
+    :definition #'merlin-locate
+    :references #'merlin-occurrences
+    :documentation #'merlin-document)
+  (defun +ocaml|init-merlin ()
+    (when (and (projectile-locate-dominating-file default-directory ".merlin")
+               (executable-find "ocamlmerlin"))
+      (merlin-mode)))
+  (add-hook 'tuareg-mode-hook #'+ocaml|init-merlin)
+
   :config
+  (map! :map tuareg-mode-map
+        :localleader
+        :n "t" #'merlin-type-enclosing
+        :n "a" #'tuareg-find-alternate-file)
   (set-company-backend! 'tuareg-mode 'merlin-company-backend)
-  (after! company
-    (remove-hook 'company-backends 'merlin-company-backend)))
+  (setq merlin-completion-with-doc t))
+
+(def-package! flycheck-ocaml
+  :when (featurep! :feature syntax-checker)
+  :after merlin
+  :config
+  ;; Disable Merlin's own error checking
+  (setq merlin-error-after-save nil)
+  ;; Enable Flycheck checker
+  (flycheck-ocaml-setup))
+
+(def-package! ocp-indent
+  ;; must be careful to always defer this, it has autoloads that adds hooks
+  ;; which we do not want if the executable can't be found
+  :defer t
+  :init
+  (defun +ocaml|init-ocp-indent ()
+    (when (executable-find "ocp-indent")
+      (ocp-setup-indent)))
+  (add-hook 'tuareg-mode-hook #'+ocaml|init-ocp-indent))
+
+(def-package! utop
+  :defer t ;; loaded by hook below
+  :when (featurep! :feature eval)
+  :init
+  (set-repl-handler! 'tuareg-mode #'utop)
+  (set-eval-handler! 'tuareg-mode #'utop-eval-region)
+  (defun +ocaml|init-utop ()
+    (when (executable-find "utop")
+      (utop-minor-mode)))
+  (add-hook 'tuareg-mode-hook #'+ocaml|init-utop))
+
+(def-package! ocamlformat
+  :after tuareg
+  :commands (ocamlformat)
+  :init
+  (set-formatter! 'ocamlformat #'ocamlformat
+    :modes '(caml-mode tuareg-mode))
+  (defun +ocaml|init-ocamlformat ()
+    (setq +format-with 'ocp-indent)
+    (when (and (executable-find "ocamlformat")
+               (locate-dominating-file default-directory ".ocamlformat"))
+      (setq +format-with 'ocamlformat)))
+  (add-hook 'tuareg-mode-hook #'+ocaml|init-ocamlformat))