infinisil/shell.nix

## shell.nix
with import <nixpkgs> {};

{ extraPackages ? (pkgs: []) }:
stdenv.mkDerivation {
  name = "test";
  buildInputs = [
    hello
  ] ++ extraPackages pkgs;
}

## test.sh
nix-shell --arg extraPackages 'p: [ p.fortune ]' --pure
	with import <nixpkgs> {};

	{ extraPackages ? (pkgs: []) }:
	stdenv.mkDerivation {
	name = "test";
	buildInputs = [
	hello
	] ++ extraPackages pkgs;
	}