Add a nix flake file

Author: harendra-kumar

.packcheck.ignore

@@ -5,5 +5,6 @@ appveyor.yml
 cabal.project
 cabal.project.user
 cabal.project.Werror
-default.nix
 stack.yaml
+flake.lock
+flake.nix

default.nix

@@ -0,0 +1,19 @@
+{
+  description = "streamly-statistics";
+
+  inputs = {
+    basepkgs.url = "git+ssh://git@github.com/composewell/streamly-packages?rev=187bde6bd362eced707ed96198ddc193af66ff42";
+    nixpkgs.follows = "basepkgs/nixpkgs";
+    nixpkgs-darwin.follows = "basepkgs/nixpkgs-darwin";
+  };
+
+  outputs = { self, nixpkgs, nixpkgs-darwin, basepkgs }:
+    basepkgs.nixpack.mkOutputs {
+      inherit nixpkgs nixpkgs-darwin basepkgs;
+      name = "streamly-statistics";
+      sources = basepkgs.nixpack.lib.localSource "streamly-statistics" ./.;
+      packages = basepkgs.nixpack.lib.devPackage "streamly-statistics";
+      #sources = import ./sources.nix;
+      #packages = import ./packages.nix;
+    };
+}