Good default for nix flakes.

flake.nix

@@ -0,0 +1,22 @@
+{
+  description = "Good basic flake template";
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils }:
+     flake-utils.lib.eachDefaultSystem (system:
+       let
+         pkgs = nixpkgs.legacyPackages.${system};
+       in
+       {
+         packages = {
+          default = pkgs.hello;
+         };
+         devShells.default = pkgs.mkShell {
+            buildInputs = with pkgs; [deno];
+         };
+       }
+     );
+}