Move :ui pretty-code to :ui ligatures

Includes a major refactor of the module.

modules/ui/ligatures/autoload/ligatures.el

@@ -0,0 +1,50 @@
+;;; ui/ligatures/autoload/ligatures.el -*- lexical-binding: t; -*-
+
+;; DEPRECATED
+;;;###autodef
+(define-obsolete-function-alias 'set-pretty-symbols! 'set-ligatures! "3.0.0")
+
+;;;###autodef
+(defun set-ligatures! (modes &rest plist)
+  "Associates string patterns with icons in certain major-modes.
+
+  MODES is a major mode symbol or a list of them.
+  PLIST is a property list whose keys must match keys in `+ligatures-classes',
+and whose values are strings representing the text to be replaced with that
+symbol. If the car of PLIST is nil, then unset any pretty symbols previously
+defined for MODES.
+
+This function accepts one special property:
+
+  :alist ALIST
+    Appends ALIST to `prettify-symbols-alist' literally, without mapping text to
+    `+ligatures-classes'.
+
+For example, the rule for emacs-lisp-mode is very simple:
+
+  (set-ligatures! 'emacs-lisp-mode
+    :lambda \"lambda\")
+
+This will replace any instances of \"lambda\" in emacs-lisp-mode with the symbol
+assicated with :lambda in `+ligatures-classes'.
+
+Pretty symbols can be unset for emacs-lisp-mode with:
+
+  (set-ligatures! 'emacs-lisp-mode nil)"
+  (declare (indent defun))
+  (if (null (car-safe plist))
+      (dolist (mode (doom-enlist modes))
+        (assq-delete-all mode +ligatures-extra-alist))
+    (let (results)
+      (while plist
+        (let ((key (pop plist)))
+          (if (eq key :alist)
+              (prependq! results (pop plist))
+            (when-let (char (plist-get +ligatures-classes key))
+              (push (cons (pop plist) char) results)))))
+      (dolist (mode (doom-enlist modes))
+        (setf (alist-get mode +ligatures-extra-alist)
+              (if-let (old-results (alist-get mode +ligatures-extra-alist))
+                  (dolist (cell results old-results)
+                    (setf (alist-get (car cell) old-results) (cdr cell)))
+                results))))))