add nix flake

flake.nix

@@ -0,0 +1,35 @@
+{
+  description = "read the ESV Bible from your terminal";
+
+  inputs = {
+    nixpkgs.url = github:NixOS/nixpkgs/nixpkgs-unstable;
+  };
+
+  outputs = { self, nixpkgs }:
+  with nixpkgs.lib;
+  let
+    forAllSystems = fn:
+      genAttrs platforms.unix (system:
+        fn (import nixpkgs {
+          inherit system;
+        })
+      );
+  in
+  {
+    packages = forAllSystems (pkgs: {
+      default = pkgs.stdenv.mkDerivation (with pkgs; {
+        name = "esv";
+        src = ./.;
+
+        nativeBuildInputs = [ ldc ];
+        buildInputs = [ curl ];
+
+        dontAddPrefix = true;
+        installFlags = [
+          "DESTDIR=$(out)"
+          "PREFIX=/"
+        ];
+      });
+    });
+  };
+}