anchor.diff:      atool
       unzip
       lzma
  -    silver-searcher
       stow
       inotifyTools
       
       # coding
       python27
       python27Packages.ipython
  -    vagrant
       haskellPackages.cabal2nix
       sloccount
       haskellPackages.hasktags
   
       # file systems
       davfs2
  -
  +    bindfs
       
     ];
   }
  
positive.code:     vim
      most
      mosh
  
      # gnupg
      gnupg
  
negative.code:   environment.systemPackages = with pkgs; [
      # main apps
      emacs 
      # firefox
      # chromium
      notmuch
      gitAndTools.gitAnnex
  
      # X11 apps
  
      # terminal apps 
      units
  