Expose our packages in flake packages output

flake.nix

@@ -3,15 +3,33 @@
 
   outputs = { self, nixpkgs, ...}:
   let
+    system = "x86_64-linux";
     pkgs = import nixpkgs {
+      inherit system;
       # For now we only support x86
-      system = "x86_64-linux";
       overlays = [ self.overlays.default ];
     };
   in
     {
       bscOverlay = import ./overlay.nix;
       overlays.default = self.bscOverlay;
-      legacyPackages.x86_64-linux = pkgs;
+
+      # full nixpkgs with our overlay applied
+      legacyPackages.${system} = pkgs;
+
+      # packages added by our overlay
+      packages.${system} =
+        let
+          inherit (builtins) attrNames removeAttrs;
+          inherit (nixpkgs.lib) flip filterAttrs getAttrs pipe isDerivation;
+        in
+          # extract the names of the packages from the overlay, then get the
+          # actual packages from the full package set with the overlay applied
+          pipe (self.overlays.default null null) [
+            attrNames
+            (flip getAttrs pkgs)
+            (flip removeAttrs [ "bsc" ])
+            (filterAttrs (_: isDerivation))
+          ];
     };
 }