Add :ui pretty-code & set-pretty-symbols! autodef

Along with defaults for C/C++, elm, elisp, js, typescript, web-mode, and
org-mode. Thanks to @ar1a for inspiration.

modules/ui/pretty-code/autoload.el

@@ -0,0 +1,86 @@
+;;; ui/pretty-code/autoload.el -*- lexical-binding: t; -*-
+
+;;;###autoload
+(defvar +pretty-code-enabled-modes
+  '(c++-mode-hook
+    c-mode-hook
+    elm-mode
+    emacs-lisp-mode
+    js2-mode
+    org-mode
+    python-mode
+    typescript-mode
+    web-mode)
+  "List of major modes in which `prettify-symbols-mode' should be enabled.")
+
+;;;###autoload
+(defvar +pretty-code-symbols
+  '(;; org
+    :name          "»"
+    :src_block     "»"
+    :src_block_end " "
+    ;; Functional
+    :lambda        "λ"
+    :def           "ƒ"
+    :composition   "∘"
+    ;; Types
+    :null          "∅"
+    :true          "𝕋"
+    :false         "𝔽"
+    :int           "ℤ"
+    :float         "ℝ"
+    :str           "𝕊"
+    :bool          "𝔹"
+    ;; Flow
+    :not           "￢"
+    :in            "∈"
+    :not-in        "∉"
+    :and           "∧"
+    :or            "∨"
+    :for           "∀"
+    :some          "∃"
+    :return        "⟼"
+    :yield         "⟻"
+    ;; Other
+    :tuple         "⨂"
+    :pipe          "")
+  "Options plist for `pretty-code-get-pairs'.")
+
+;; When you get to the right edge, it goes back to how it normally prints
+;;;###autoload
+(setq prettify-symbols-unprettify-at-point 'right-edge)
+
+;;;###autodef
+(defun set-pretty-symbols! (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 `+pretty-code-symbols',
+and whose values are strings representing the text to be replaced with that
+symbol.
+
+For example, the rule for emacs-lisp-mode is very simple:
+
+  (set-pretty-symbols! 'emacs-lisp-mode
+    :lambda \"lambda\")
+
+This will replace any instances of \"lambda\" in emacs-lisp-mode with the symbol
+assicated with :lambda in `+pretty-code-symbols'."
+  (declare (indent 1))
+  (dolist (mode (doom-enlist modes))
+    (let ((fn (intern (format "+pretty-code|init-%s" mode))))
+      (fset fn
+            (lambda ()
+              (when (and (eq major-mode mode)
+                         (memq major-mode +pretty-code-enabled-modes))
+                (let (results prop icon)
+                  (while plist
+                    (let ((prop (pop plist))
+                          (sym  (pop plist)))
+                      (when-let* ((icon (plist-get +pretty-code-symbols prop)))
+                        (push (cons sym (prettify-utils-string icon))
+                              results))))
+                  (setq prettify-symbols-alist results))
+                (prettify-symbols-mode -1)
+                (prettify-symbols-mode +1))))
+      (add-hook (intern (format "%s-hook" mode)) fn))))