add flake

flake.nix

@@ -0,0 +1,34 @@
+{
+  inputs = {
+    flake-utils.url = "github:numtide/flake-utils";
+    naersk.url = "github:nix-community/naersk";
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+  };
+
+  outputs = { self, flake-utils, naersk, nixpkgs }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = (import nixpkgs) {
+          inherit system;
+        };
+        naersk' = pkgs.callPackage naersk { };
+      in
+      rec {
+        defaultPackage = naersk'.buildPackage
+          {
+            src = ./.;
+            buildInputs = with pkgs; [ openssl pkg-config ];
+          };
+
+        devShell = pkgs.mkShell {
+          buildInputs = with pkgs; [
+            openssl
+            pkg-config
+            clippy
+            rust-analyzer
+          ];
+          nativeBuildInputs = with pkgs; [ rustc cargo ];
+        };
+      }
+    );
+}