Expose our packages in flake packages output

flake.nix

@@ -2,17 +2,34 @@
   inputs.nixpkgs.url = "nixpkgs";
 
   outputs = { self, nixpkgs, ...}:
-  let
-    pkgs = import nixpkgs {
+    let
       # For now we only support x86
       system = "x86_64-linux";
-      overlays = [ self.overlays.default ];
-    };
-  in
+      pkgs = import nixpkgs {
+        inherit system;
+        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 { inherit (nixpkgs) lib; }) [
+          attrNames
+          (flip getAttrs pkgs)
+          (flip removeAttrs [ "bsc" ])
+          (filterAttrs (_: isDerivation))
+        ];
 
       # propagate nixpkgs lib, so we can do bscpkgs.lib
       inherit (nixpkgs) lib;