Towards a declarative dependency management solution for emacs

canonical_el-get.el

;; canonical list                                                                                                                                               
(defvar my-packages
  '(ack haskell-mode ruby-mode coffee-mode deft expand-region
                   gist inf-ruby magit yaml-mode)                 
  "Canonical list of packages.")
(el-get-cleanup my-packages)                                                                                                                                    
(el-get 'sync my-packages)  

canonical_package.el

(require 'cl)
(defvar my-packages
  '(ack haskell-mode ruby-mode coffee-mode deft expand-region
                   gist inf-ruby magit yaml-mode)                 
  "Canonical list of packages.")
(defun my-packages-installed-p ()
     (every 'package-installed-p my-packages))
(unless (my-packages-installed-p)
  (message "%s" "Emacs is now refreshing its package database...")
  (package-refresh-contents)
  (message "%s" " done.")
  ;; install the missing packages
  (loop for p in my-packages
    unless (package-installed-p p)
     do (package-install p)))

el-get-cleanup.el

(defun el-get-cleanup (packages)
  "Remove packages not explicitly declared"
  (let* ((packages-to-keep (el-get-dependencies (mapcar 'el-get-as-symbol packages)))
         (packages-to-remove (set-difference (mapcar 'el-get-as-symbol
                                                     (el-get-list-package-names-with-status
                                                      "installed")) packages-to-keep)))
    (mapc 'el-get-remove packages-to-remove)))

gistfile1.txt

*
!init.el
!.gitignore

install_el-get_in_scratch.el

;; So the idea is that you copy/paste this code into your *scratch* buffer,
;; hit C-j, and you have a working developper edition of el-get.
(url-retrieve
 "https://raw.github.com/dimitri/el-get/master/el-get-install.el"
 (lambda (s)
   (let (el-get-master-branch)
     (goto-char (point-max))
     (eval-print-last-sexp))))