error: Dependency is not of a valid type: element 1 of nativeBuildInputs for nix-shell

Question

I am working on a simple nix environment where I want to run a script which generates shell script output that should (according to a complex web of rules) initialize a bunch of env vars in my env.

However, I am taken aback by a cryptic error message.

1. What am I doing wrong?
2. (In general: How do I define a derivation that I then can run as part of my shell initialization?)

Code

{ pkgs ? import <nixpkgs> {} }:
pkgs.mkShell {
  packages = with pkgs; [
    pkgs.stdenv.mkDerivation {
      deps = [];
      buildInputs = [];
      src = "hi";
      name = "hello";
      stdenv = "./";

    }
  ];

  shellHook = "echo " + "hi;";
}

Result

$ nix-shell "./dev-env.nix"

error:
       … while calling the 'derivationStrict' builtin

         at /builtin/derivation.nix:9:12: (source not available)

       … while evaluating derivation 'nix-shell'
         whose name attribute is located at /nix/store/ka3vmkgvsn6cj8dywj7n1xl3bm54gxm7-source/pkgs/stdenv/generic/make-derivation.nix:352:7

       … while evaluating attribute 'nativeBuildInputs' of derivation 'nix-shell'

         at /nix/store/ka3vmkgvsn6cj8dywj7n1xl3bm54gxm7-source/pkgs/stdenv/generic/make-derivation.nix:396:7:

          395|       depsBuildBuild              = elemAt (elemAt dependencies 0) 0;
          396|       nativeBuildInputs           = elemAt (elemAt dependencies 0) 1;
             |       ^
          397|       depsBuildTarget             = elemAt (elemAt dependencies 0) 2;

       error: Dependency is not of a valid type: element 1 of nativeBuildInputs for nix-shell