A good starter dev shell template flake.nix

flake.nix

{
  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
    flake-utils.url = "github:numtide/flake-utils";
  };

  outputs =
    { nixpkgs, flake-utils, ... }:
    flake-utils.lib.eachDefaultSystem (
      system:
      let
        pkgs = nixpkgs.legacyPackages.${system};
      in
      {
        devShells.default = pkgs.mkShell {
          packages = [
            pkgs.cowsay
            pkgs.git
            pkgs.uv
            pkgs.nushell
          ];

          # if you use zsh, uncomment the following block
          # shellHook = ''
          #   zsh
          # '';
        };
      }
    );
}