improve overlay

flake.nix

@@ -22,7 +22,7 @@
     flake-utils.lib.eachDefaultSystem (system: let
       pkgs = import nixpkgs {
         inherit system;
-        overlays = [self.overlays.${system}.default];
+        overlays = [self.overlays.default];
       };
     in {
       formatter = pkgs.alejandra;
@@ -30,21 +30,23 @@
         inherit (import "${dhall-haskell}/nix/shared.nix" {inherit system;}) dhall dhall-nix dhall-nixpkgs;
         dhall-nix-lib = pkgs.dhallPackages.callPackage ./package.nix {};
       };
-      overlays.default = _: prev:
-        self.packages.${system}
+      devShells.default = pkgs.mkShell {
+        nativeBuildInputs = [self.packages.${system}.dhall self.packages.${system}.dhall-nix];
+      };
+      lib.dhallToNix = import ./dhallToNix.nix {inherit pkgs;};
+    })
     // {
+      overlays.default = final: prev: {
         dhallPackages = prev.dhallPackages.override (self: {
           overrides = self: super: {
             Prelude = super.Prelude.overridePackage {
               rev = "v22.0.0";
               sha256 = "157x95yw9hibpifa8figawgclnc1d1bapmbp1zw60l2viy936b83";
             };
+            inherit (self.packages.${prev.emptyDirectory.system}) dhall-nix-lib;
           };
         });
+        inherit (self.packages.${prev.system}) dhall dhall-nix dhall-nixpkgs;
       };
-      devShells.default = pkgs.mkShell {
-        nativeBuildInputs = [self.packages.${system}.dhall self.packages.${system}.dhall-nix];
     };
-      lib.dhallToNix = import ./dhallToNix.nix {inherit pkgs;};
-    });
 }

package.nix

@@ -3,7 +3,7 @@
   Prelude,
 }:
 buildDhallDirectoryPackage {
-  name = ".";
+  name = "dhall-nix-lib";
   src = ./.;
   file = "package.dhall";
   source = false;