feat(sml): add treesit (and lsp) support

modules/lang/sml/README.org

@@ -4,17 +4,23 @@
 #+since:    21.12.0
 
 * Description :unfold:
-THis module adds [[https://smlfamily.github.io/][SML (Standard ML) programming language]] support to Doom Emacs.
+This module adds [[https://smlfamily.github.io/][SML (Standard ML) programming language]] support to Doom Emacs.
 
 ** Maintainers
 *This module needs a maintainer.* [[doom-contrib-maintainer:][Become a maintainer?]]
 
 ** Module flags
-/This module has no flags./
+- +lsp ::
+  Enable LSP support for ~sml-mode~/~sml-ts-mode~. Requires [[doom-module::tools lsp]]
+  and a langserver (supports [[https://github.com/azdavis/millet][millet-ls]]).
+- +tree-sitter ::
+  Leverages tree-sitter for better syntax highlighting and structural text
+  editing. Requires [[doom-module::tools tree-sitter]].
 
 ** Packages
 - [[doom-package:company-mlton]] if [[doom-module::completion company]]
 - [[doom-package:sml-mode]]
+- [[doom-package:sml-ts-mode]] if [[doom-module:+tree-sitter]]
 
 ** Hacks
 /No hacks documented for this module./

modules/lang/sml/config.el

@@ -3,11 +3,14 @@
 (use-package! sml-mode
   :mode "\\.s\\(?:ml\\|ig\\)\\'"
   :config
-  (set-repl-handler! 'sml-mode #'run-sml)
-  (set-formatter! 'smlformat '("smlformat") :modes '(sml-mode))
+  (set-repl-handler! '(sml-mode sml-ts-mode) #'run-sml)
+  (set-formatter! 'smlformat '("smlformat") :modes '(sml-mode sml-ts-mode))
+
+  (when (modulep! +lsp)
+    (add-hook 'sml-mode-local-vars-hook #'lsp! 'append))
 
   ;; don't auto-close apostrophes (type 'a = foo) and backticks (`Foo)
-  (sp-with-modes 'sml-mode
+  (sp-with-modes '(sml-mode sml-ts-mode)
     (sp-local-pair "'" nil :actions nil)
     (sp-local-pair "`" nil :actions nil))
 
@@ -23,6 +26,19 @@
         :desc "Run region"                  "r" #'sml-prog-proc-send-region))
 
 
+;; TODO: Mirror sml-mode keybinds to ts-mode
+(use-package! sml-ts-mode
+  :when (modulep! +tree-sitter)
+  :when (fboundp 'treesit-available-p)
+  :defer t
+  :init
+  (set-tree-sitter! 'sml-mode 'sml-ts-mode
+    '((sml :url "https://github.com/MatthewFluet/tree-sitter-sml")))
+  :config
+  (when (modulep! +lsp)
+    (add-hook 'sml-ts-mode-local-vars-hook #'lsp! 'append)))
+
+
 (use-package! company-mlton
   :when (modulep! :completion company)
   :hook (sml-mode . company-mlton-init)

modules/lang/sml/doctor.el

@@ -1,5 +1,9 @@
 ;;; lang/sml/doctor.el -*- lexical-binding: t; -*-
 
+(assert! (or (not (modulep! +tree-sitter))
+             (modulep! :tools tree-sitter))
+         "This module requires (:tools tree-sitter)")
+
 (when (modulep! :editor format)
   (unless (executable-find "smlformat")
     (warn! "Couldn't find smlformat. Formatting will be disabled.")))

modules/lang/sml/packages.el

@@ -6,3 +6,5 @@
   (package! company-mlton
     :recipe (:host github :repo "MatthewFluet/company-mlton" :files ("*.el" "*.basis"))
     :pin "9b09d209b4767a2af24784fb5321390ed1d445bf"))
+(when (modulep! +tree-sitter)
+  (package! sml-ts-mode :pin "d2dabcc9d8f91eeee7048641e4c80fabb3583194"))