feat(racket): add +hash-lang

`racket-mode` recently added `racket-hash-lang-mode` as an alternative
major mode.

Close: #7543
Co-authored-by: hlissner <hlissner@users.noreply.github.com>

modules/lang/racket/README.org

@@ -14,8 +14,12 @@ This module adds support for the [[https://www.racket-lang.org/][Racket programm
   Enable support for ~racket-mode~. Requires [[doom-module::tools lsp]] and a langserver
   (supports [[https://github.com/jeapostrophe/racket-langserver][racket-langserver]]).
 - +xp ::
-  Enable the explore mode (~racket-xp-mode~), which "analyzes expanded code to
+  Enable the explore minor mode (~racket-xp-mode~), which "analyzes expanded
-  explain and explore."
+  code to explain and explore."
+- +hash-lang ::
+  Enable the hash-lang major mode (~racket-hash-lang-mode~), which "uses
+  color-lexer, indent, and navigation supplied by a #lang." This flag can be
+  used along with the ~+xp~ flag.
 
 ** Packages
 - [[doom-package:racket-mode]]

modules/lang/racket/config.el

@@ -8,31 +8,49 @@
 ;;
 ;;; Packages
 
+(let (mode
+      mode-map
+      mode-exts
+      mode-hook
+      mode-local-vars-hook)
+  (if (modulep! +hash-lang)
+      (setq mode 'racket-hash-lang-mode
+            mode-exts '("\\.rkt\\'"    ; Racket
+                        "\\.scrbl\\'"  ; Scribble
+                        "\\.rhm\\'"))  ; Rhombus
+    (setq mode 'racket-mode
+          mode-exts `("\\.rkt\\'")))
+  (let ((mode-name (symbol-name mode)))
+    (setq mode-map (intern (format "%s-map" mode-name))
+          mode-hook (intern (format "%s-hook" mode-name))
+          mode-local-vars-hook (intern (format "%s-local-vars-hook" mode-name))))
+
   (use-package! racket-mode
-  :mode "\\.rkt\\'"  ; give it precedence over :lang scheme
+    :defer t
+    :init
+    (dolist (entry mode-exts)
+      (add-to-list 'auto-mode-alist (cons entry mode)))
     :config
-  (set-repl-handler! 'racket-mode #'+racket/open-repl)
+    (set-repl-handler! mode #'+racket/open-repl)
-  (set-lookup-handlers! '(racket-mode racket-repl-mode)
+    (set-lookup-handlers! `(,mode racket-repl-mode)
       :definition    #'+racket-lookup-definition
       :documentation #'+racket-lookup-documentation)
-  (set-docsets! 'racket-mode "Racket")
+    (set-docsets! mode "Racket")
-  (set-ligatures! 'racket-mode
+    (set-ligatures! mode
       :lambda  "lambda"
       :map     "map"
       :dot     ".")
-  (set-rotate-patterns! 'racket-mode
+    (set-rotate-patterns! mode :symbols '(("#true" "#false")))
-    :symbols '(("#true" "#false")))
+    (set-formatter! 'raco-fmt '("raco" "fmt") :modes (list mode))
-  (set-formatter! 'raco-fmt '("raco" "fmt") :modes '(racket-mode))
 
-  (add-hook! 'racket-mode-hook
+    (add-hook mode-hook #'rainbow-delimiters-mode)
-             #'rainbow-delimiters-mode
+    (add-hook mode-hook #'highlight-quoted-mode)
-             #'highlight-quoted-mode)
 
     (when (modulep! +lsp)
-    (add-hook 'racket-mode-local-vars-hook #'lsp! 'append))
+      (add-hook mode-local-vars-hook #'lsp! 'append))
 
     (when (modulep! +xp)
-    (add-hook 'racket-mode-local-vars-hook #'racket-xp-mode)
+      (add-hook mode-local-vars-hook #'racket-xp-mode)
       ;; Both flycheck and racket-xp produce error popups, but racket-xp's are
       ;; higher quality so disable flycheck's:
       (when (modulep! :checkers syntax)
@@ -42,7 +60,7 @@
 
     (unless (or (modulep! :editor parinfer)
                 (modulep! :editor lispy))
-    (add-hook 'racket-mode-hook #'racket-smart-open-bracket-mode))
+      (add-hook mode-hook #'racket-smart-open-bracket-mode))
 
     (map! (:map racket-xp-mode-map
            [remap racket-doc]              #'racket-xp-documentation
@@ -50,7 +68,7 @@
            [remap next-error]              #'racket-xp-next-error
            [remap previous-error]          #'racket-xp-previous-error)
           (:localleader
-         :map racket-mode-map
+           :map ,mode-map
            "a" #'racket-align
            "A" #'racket-unalign
            "f" #'racket-fold-all-tests
@@ -92,4 +110,4 @@
            (:prefix ("g" . "goto")
             "b" #'racket-unvisit
             "m" #'racket-visit-module
-          "d" #'racket-repl-visit-definition))))
+            "d" #'racket-repl-visit-definition)))))