A very simple starting derivation for nix shell

pkgs.nix

import (fetchTarball {
  url =  https://github.com/NixOS/nixpkgs/archive/ab3adfe1c769c22b6629e59ea0ef88ec8ee4563f.tar.gz;
  sha256 = "1m4wvrrcvif198ssqbdw897c8h84l0cy7q75lyfzdsz9khm1y2n1";
})

shell.nix

let
  inherit (pkgs) mkShell beam;
  pkgs = import ./pkgs.nix {} ;
in mkShell {
  nativeBuildInputs = [ beam.interpreters.elixir_1_10 ];
}