init.el

(require 'package)
(setq package-user-dir "~/.emacs.d/elpa/")
(add-to-list 'package-archives
             '("marmalade" . "http://marmalade-repo.org/packages/") t)
(add-to-list 'package-archives
             '("melpa" . "http://melpa.milkbox.net/packages/") t)
(setq package-archive-exclude-alist '(("melpa" paredit)))
(package-initialize)

(defmacro require! (package)
  `(progn
     (when (not (package-installed-p ,package))
       (package-install ,package))
     (require ,package)))