Switch flake.nix architecture

flake.nix

@@ -1,7 +1,3 @@
-# SPDX-FileCopyrightText: 2021 Serokell <https://serokell.io/>
-#
-# SPDX-License-Identifier: CC0-1.0
-
 {
   description = "Conway's Game of Life in Haskell";
 
@@ -13,44 +9,48 @@
   outputs = { self, nixpkgs, flake-utils, ... }:
     flake-utils.lib.eachDefaultSystem (system:
       let
-        pkgs = nixpkgs.legacyPackages.${system};
-
-        haskellPackages = pkgs.haskellPackages;
-
-        jailbreakUnbreak = pkg:
-          pkgs.haskell.lib.doJailbreak (pkg.overrideAttrs (_: { meta = { }; }));
-
-        packageName = "conways-game-of-life";
-
+        overlays = [ ];
+        pkgs = import nixpkgs { inherit system overlays; config.allowBroken = true; };
         execName = "gol";
-      in {
-        packages.${packageName} =
-          haskellPackages.callCabal2nix packageName self rec {
-            # Dependency overrides go here
+        hp = pkgs.haskellPackages; # pkgs.haskell.packages.ghc921;
+        project = returnShellEnv:
+          hp.developPackage {
+            inherit returnShellEnv;
+            name = "conways-game-of-life";
+            root = ./.;
+            withHoogle = false;
+            overrides = self: super: with pkgs.haskell.lib; {
+              # Use callCabal2nix to override Haskell dependencies here
+              # cf. https://tek.brick.do/K3VXJd8mEKO7
+              # Example: 
+              # > NanoID = self.callCabal2nix "NanoID" inputs.NanoID { };
+              # Assumes that you have the 'NanoID' flake input defined.
+            };
+            modifier = drv:
+              pkgs.haskell.lib.addBuildTools drv (with hp; [
+                # Specify your build/dev dependencies here. 
+                ghc
+                cabal-install
+                hlint
+                haskell-language-server
+                ormolu
+
+                pkgs.mesa
+                pkgs.mesa_glu
+                pkgs.freeglut
+              ]);
           };
+      in
+      {
+        # Used by `nix build` & `nix run` (prod exe)
+        defaultPackage = project false;
 
-        defaultPackage = self.packages.${system}.${packageName};
-
-        apps.${execName} = {
+        defaultApp = {
           type = "app";
-          program = "${self.packages.${system}.${packageName}}/bin/${execName}";
+          program = "${self.defaultPackage.${system}}/bin/${execName}";
         };
 
-        defaultApp = self.apps.${system}.${execName};
-
-        devShell = pkgs.mkShell {
-          buildInputs = with haskellPackages; [
-            ghc
-            cabal-install
-            hlint
-            pkgs.haskell-language-server
-            pkgs.ormolu
-
-            pkgs.mesa
-            pkgs.mesa_glu
-            pkgs.freeglut
-          ];
-          inputsFrom = builtins.attrValues self.packages.${system};
-        };
+        # Used by `nix develop` (dev shell)
+        devShell = project true;
       });
 }