Add support for building natter via nix.

flake.nix

@@ -0,0 +1,86 @@
+{
+  description = "Natter static site generator";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    rust-overlay = {
+      url = "github:oxalica/rust-overlay";
+      inputs = {
+        nixpkgs.follows = "nixpkgs";
+      };
+    };
+  };
+
+  outputs =
+    {
+      self,
+      nixpkgs,
+      rust-overlay,
+    }:
+    let
+      forAllSystems =
+        func:
+        builtins.listToAttrs (
+          map (system: {
+            name = system;
+            value = func system;
+          }) nixpkgs.lib.systems.flakeExposed
+        );
+    in
+    {
+      devShells = forAllSystems (
+        system:
+        let
+          overlays = [ (import rust-overlay) ];
+          pkgs = import nixpkgs {
+            inherit system overlays;
+          };
+          rustToolchain = (pkgs.rust-bin.fromRustupToolchainFile ./rust-toolchain.toml);
+        in
+        {
+          default = pkgs.mkShell {
+            nativeBuildInputs = [
+              rustToolchain
+            ];
+            buildInputs = with pkgs; [
+            ];
+          };
+        }
+      );
+      packages = forAllSystems (
+        system:
+        let
+          overlays = [ (import rust-overlay) ];
+          pkgs = import nixpkgs {
+            inherit system overlays;
+          };
+          appliedOverlay = self.overlays.default pkgs pkgs;
+        in
+        rec {
+          default = release;
+          inherit (appliedOverlay.natter)
+            release
+            ;
+          docker_env = pkgs.buildEnv {
+            name = "natter";
+            paths = with pkgs; [
+              appliedOverlay.natter.release
+              bash
+              uutils-coreutils-noprefix
+              # toybox # Smaller than uutils-coreutils?
+            ];
+          };
+        }
+      );
+      overlays.default = final: prev: {
+        natter = final.lib.makeScope final.newScope (natterScope: {
+          release = (
+            natterScope.callPackage ./nix/package.nix {
+              inherit rust-overlay;
+              buildType = "lto";
+            }
+          );
+        });
+      };
+    };
+}