Remove overlay.nix

flake.nix

@@ -10,13 +10,28 @@
     let
       ghcVersion = "963";
       compiler = "ghc${ghcVersion}";
-      overlay = import ./overlay.nix compiler;
-      overlays = [ overlay ];
     in
     flake-utils.lib.eachDefaultSystem
       (system:
         let
-          pkgs = import nixpkgs { inherit system overlays; };
+          pkgs = import nixpkgs { inherit system; };
+          hsPkgs = pkgs.haskell.packages.${compiler}.override (old: {
+            overrides = pkgs.lib.composeExtensions (old.overrides or (_: _: { }))
+              (hfinal: hprev: {
+                kindly-functors = hfinal.callCabal2nix "kindly-functors" (pkgs.fetchFromGitHub {
+                  owner = "solomon-b";
+                  repo = "kindly-functors";
+                  rev = "26fdb99ef92124241e38e6f4511961ad2f9fb920";
+                  sha256 = "sha256-nZHERb1QA3XtRZWEcIoq8P4atOBioE7cRrJqrjkw9m0=";
+                }) {};
+                monoidal-functors = (hfinal.callCabal2nix "monoidal-functors" ./. { }).overrideScope (hfinal': hprev': {
+                  bifunctors = hfinal.bifunctors_5_6_1;
+                  semigroupoids = hfinal.semigroupoids_6_0_0_1.overrideScope (hfinal': hprev': {
+                    bifunctors = hfinal.bifunctors_5_6_1;
+                  });
+                });
+              });
+          });
         in
         rec {
           devShell = pkgs.mkShell {
@@ -31,11 +46,9 @@
 
           formatter = pkgs.nixpkgs-fmt;
           packages = flake-utils.lib.flattenTree {
-            monoidal-functors = pkgs.haskellPackages.monoidal-functors;
+            monoidal-functors = hsPkgs.monoidal-functors;
           };
 
           defaultPackage = packages.monoidal-functors;
-        }) // {
-      overlays.default = overlay;
-    };
+        });
 }