Add nix flake

.envrc

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+# ^ added for shellcheck and file-type detection
+
+# Watch & reload direnv on change
+watch_file flake.nix
+
+if [[ $(type -t use_flake) != function ]]; then
+  echo "ERROR: use_flake function missing."
+  echo "Please update direnv to v2.30.0 or later."
+  exit 1
+fi
+use flake

.gitignore

@@ -1,2 +1,3 @@
 /target
 /testrepos
+result

flake.nix

@@ -0,0 +1,22 @@
+{
+  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 = ./.; };
+
+        devShell = pkgs.mkShell {
+          nativeBuildInputs = with pkgs; [ rustc cargo plantuml cargo-release ];
+        };
+      });
+}