Example of Nix's option expansion

example-1.nix

{
  programs.zsh.enable = true;
  programs.zsh.enableAutosuggestions = true;
  programs.zsh.envExtra = ''
    export MYVAR="true"
    export MYVAR2="false"
  '';
}

example-2.nix

{
  programs.zsh = {
    enable = true;
    enableAutosuggestions = true;
    envExtra = ''
      export MYVAR="true"
      export MYVAR2="false"
    '';
  };
}