Add flake.nix

flake.nix

@@ -0,0 +1,23 @@
+{
+  name = "nixpkgs";
+
+  epoch = 2019;
+
+  description = "A collection of packages for the Nix package manager";
+
+  provides = flakes:
+    let pkgs = import ./. {}; in
+    {
+      lib = import ./lib;
+
+      builders = {
+        inherit (pkgs) stdenv fetchurl;
+      };
+
+      packages = {
+        inherit (pkgs) hello nix fuse nlohmann_json boost;
+      };
+
+      legacyPkgs = pkgs;
+    };
+}