add undo-tree-mode properly

packages.el

@@ -66,8 +66,13 @@
 (use-package geiser
   :ensure t)
 
-;; (use-package undo-tree
-;;   :ensure t)
+(use-package undo-tree
+  :ensure t
+  :bind
+  ("C-_" . 'undo-tree-undo)
+  ("M-_" . 'undo-tree-redo)
+  :config
+  (global-undo-tree-mode)) 
 
 (use-package dashboard
   :ensure t
@@ -96,7 +101,10 @@
   (global-set-key (kbd "C->") 'mc/mark-next-like-this))
 
 (use-package paredit
-  :ensure t)
+  :ensure t
+  :config
+  (add-hook 'scheme-mode-hook 'paredit-mode)
+  (add-hook 'lisp-mode-hook 'paredit-mode))
 
 ;; jump to definitions and files with M-.
 (use-package dumb-jump