gistfile1.el

;;method to check if all packages are installed
(defun packages-installed-p ()
  (loop for p in required-packages
	when (not (package-installed-p p)) do (return nil)
	finally (return t)))

;;if not all packages are installed, check one by one and install the missing ones
(unless (packages-installed-p)
  ;;check for new packages
  (message "%s" "Emacs is now refreshing its package database...")
  (package-refresh-contents)
  (message "%s" "done!")
  ;;install the missing packages
  (dolist (p required-packages)
    (when (not (package-installed-p p))
      (package-install p))))