Add nix flake

Author: triarius

.gitignore

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

flake.lock

@@ -0,0 +1,66 @@
+{
+  description = "A modern Rust project environment using Nix and Crane";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    crane.url = "github:ipetkov/crane";
+    systems.url = "github:nix-systems/default";
+  };
+
+  outputs = { self, nixpkgs, crane, systems, ... }:
+    let
+      forEachSystem = f: nixpkgs.lib.genAttrs (import systems) (system: f rec {
+        pkgs = import nixpkgs { inherit system; };
+        craneLib = crane.mkLib pkgs;
+        src = let
+          fixturesFilter = path: _type: builtins.match ".*/examples/.*" path != null;
+          fixturesOrCargo = path: type: (fixturesFilter path type) || (craneLib.filterCargoSources path type);
+        in pkgs.lib.cleanSourceWith {
+          src = craneLib.path ./.;
+          filter = fixturesOrCargo;
+        };
+      });
+    in
+    {
+      packages = forEachSystem ({ pkgs, craneLib, src }:
+        let
+          commonArgs = {
+            inherit src;
+            strictDeps = true;
+            nativeBuildInputs = with pkgs; [ pkg-config ];
+            buildInputs = with pkgs; [
+              openssl
+            ] ++ pkgs.lib.optionals pkgs.stdenv.isDarwin [
+              pkgs.darwin.apple_sdk.frameworks.Security
+              pkgs.darwin.apple_sdk.frameworks.SystemConfiguration
+            ];
+          };
+
+          # Build *only* the dependencies to cache them in the Nix store
+          cargoArtifacts = craneLib.buildDepsOnly commonArgs;
+        in
+        {
+          default = craneLib.buildPackage (commonArgs // {
+            inherit cargoArtifacts;
+          });
+        }
+      );
+
+      devShells = forEachSystem ({ pkgs, craneLib, src }: {
+        default = craneLib.devShell {
+          inputsFrom = [ self.packages.${pkgs.system}.default ];
+          packages = with pkgs; [
+            cargo
+            rustc
+            rust-analyzer
+            rustfmt
+            clippy
+          ];
+          env = {
+            RUST_SRC_PATH = "${pkgs.rustPlatform.rustLibSrc}";
+            RUST_BACKTRACE = "1";
+          };
+        };
+      });
+    };
+}