override only the source, keep original derivation

Author: liesnikov

flake.nix

@@ -8,14 +8,15 @@
     flake-utils.lib.eachDefaultSystem (system:
       let
         pkgs = import nixpkgs {inherit system;};
+        agdasrc = pkgs.fetchFromGitHub {
+          owner = "agda";
+          repo = "agda";
+          rev = "5c29109f8212ef61b0091d62ef9c8bfdfa16cf36";
+          hash = "sha256-qiV/tk+/b3xYPJcWVVd7x9jrQjBzl1TXHPNEQbKV2rA=";
+        };
         hpkgs = with pkgs; haskellPackages.override {
-          overrides = haskell.lib.packageSourceOverrides {
-            Agda = fetchFromGitHub {
-              owner = "agda";
-              repo = "agda";
-              rev = "5c29109f8212ef61b0091d62ef9c8bfdfa16cf36";
-              hash = "sha256-qiV/tk+/b3xYPJcWVVd7x9jrQjBzl1TXHPNEQbKV2rA=";
-            };
+          overrides = _: old: rec {
+            Agda = haskell.lib.overrideSrc old.Agda {src = agdasrc;};
           };
         };
         agda2lambox = hpkgs.callCabal2nix "agda2lambox" ./. {};