Add Nix flake and direnv files.

.envrc

@@ -0,0 +1,3 @@
+#!/usr/bin/env bash
+
+use flake

.gitignore

@@ -1,9 +1,5 @@
-# Generated by Cargo
-debug/
-target/
-
-# Code coverage results
+.direnv/
 coverage/
-
-# mdBook output
+debug/
 hooked-book/book/
+target/

flake.lock

@@ -0,0 +1,59 @@
+{
+  "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1705309234,
+        "narHash": "sha256-uNRRNRKmJyCRC/8y1RqBkqWBLM034y4qN7EprSdmgyA=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "1ef2e671c3b0c19053962c07dbda38332dcebf26",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1705403940,
+        "narHash": "sha256-bl7E3w35Bleiexg01WsN0RuAQEL23HaQeNBC2zjt+9w=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "f0326542989e1bdac955ad6269b334a8da4b0c95",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "type": "indirect"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,13 @@
+{
+  inputs.flake-utils.url = "github:numtide/flake-utils";
+
+  outputs = { self, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+      in
+      {
+        devShells.default = import ./shell.nix { inherit pkgs; };
+      }
+    );
+}

shell.nix

@@ -0,0 +1,7 @@
+{ pkgs ? import <nixpkgs> { } }:
+
+with pkgs;
+
+mkShell rec {
+  packages = [ cargo-make mdbook ];
+}