different_versions_of_nixpkgs.nix

with (import <nixpkgs> {});
let
  v_old_1 = import (builtins.fetchTarball https://github.com/nixos/nixpkgs/archive/${sha1}.tar.gz) {}.;
  v_old_2 = import (builtins.fetchTarball https://github.com/nixos/nixpkgs/archive/${sha1}.tar.gz) {}.;
  v_old_3 = import (builtins.fetchTarball https://github.com/nixos/nixpkgs/archive/${sha1}.tar.gz) {}.;
 in
 {
   myPackage = stdenv.mkDerivation rec {
     name = "different-editor-versions";
     buildInputs = [v_old1.emacs v_old2.vi];
     
     nano = pkgs.writeScript "special-nano" ''
        #!${v_old_3.bash}/bin/bash
        # do shit
        ${v_old3.nano} $@
     '';
   };
}