diff --git a/config.nix b/config.nix
new file mode 100644
index 00000000..e2917d3b
--- /dev/null
+++ b/config.nix
@@ -0,0 +1,22 @@
+{
+  home = {
+    username = "william";
+    fullname = "William Hsieh";
+    email = "wh31110@gmail.com";
+    dotDir = "dotfiles"; # path relative to $HOME, this example represents `~/dotfiles`
+    wsl = false;
+    gui = false;
+  };
+
+  nixos = {
+    # enable = true;
+    hostname = "nixos-local";
+    system = "x86_64-linux";
+  };
+
+  darwin = {
+    # enable = true;
+    hostname = "macos-local";
+    system = "aarch64-darwin";
+  };
+}
diff --git a/flake.lock b/flake.lock
index accc270f..aa3e5ea6 100644
--- a/flake.lock
+++ b/flake.lock
@@ -15,6 +15,26 @@
         "type": "github"
       }
     },
+    "darwin": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1724994893,
+        "narHash": "sha256-yutISDGg6HUaZqCaa54EcsfTwew3vhNtt/FNXBBo44g=",
+        "owner": "LnL7",
+        "repo": "nix-darwin",
+        "rev": "c8d3157d1f768e382de5526bb38e74d2245cad04",
+        "type": "github"
+      },
+      "original": {
+        "owner": "LnL7",
+        "repo": "nix-darwin",
+        "type": "github"
+      }
+    },
     "flake-compat": {
       "flake": false,
       "locked": {
@@ -96,26 +116,6 @@
         "type": "github"
       }
     },
-    "nix-darwin": {
-      "inputs": {
-        "nixpkgs": [
-          "nixpkgs"
-        ]
-      },
-      "locked": {
-        "lastModified": 1724561770,
-        "narHash": "sha256-zv8C9RNa86CIpyHwPIVO/k+5TfM8ZbjGwOOpTe1grls=",
-        "owner": "LnL7",
-        "repo": "nix-darwin",
-        "rev": "ac5694a0b855a981e81b4d9f14052e3ff46ca39e",
-        "type": "github"
-      },
-      "original": {
-        "owner": "LnL7",
-        "repo": "nix-darwin",
-        "type": "github"
-      }
-    },
     "nix-index-database": {
       "inputs": {
         "nixpkgs": [
@@ -187,9 +187,9 @@
     "root": {
       "inputs": {
         "catppuccin": "catppuccin",
+        "darwin": "darwin",
         "git-hooks": "git-hooks",
         "home-manager": "home-manager",
-        "nix-darwin": "nix-darwin",
         "nix-index-database": "nix-index-database",
         "nixpkgs": "nixpkgs",
         "nixpkgs-unstable": "nixpkgs-unstable"
diff --git a/flake.nix b/flake.nix
index c09c3807..3e93af20 100644
--- a/flake.nix
+++ b/flake.nix
@@ -25,7 +25,7 @@
       inputs.nixpkgs.follows = "nixpkgs";
     };
 
-    nix-darwin = {
+    darwin = {
       url = "github:LnL7/nix-darwin";
       inputs.nixpkgs.follows = "nixpkgs";
     };
@@ -42,10 +42,12 @@
   };
 
   outputs = inputs @ { self, nixpkgs, home-manager, ... }:
+    with self.lib;
     let
       system = "x86_64-linux";
+      foreachSystem = genAttrs [ "x86_64-linux" "aarch64-darwin" ];
+
       username = (import ./home/config.nix).user;
-      hostname = (import ./system/config.nix).host;
 
       # https://github.com/nix-community/home-manager/issues/2942#issuecomment-1378627909
       pkgs = import nixpkgs {
@@ -64,7 +66,9 @@
       inherit (self) outputs;
     in
     {
-      packages.${system}.default = home-manager.defaultPackage.${system};
+      lib = import ./lib { inherit inputs; } // inputs.nixpkgs.lib;
+
+      # packages.${system}.default = home-manager.defaultPackage.${system};
 
       homeConfigurations = {
         ${username} = home-manager.lib.homeManagerConfiguration {
@@ -77,36 +81,12 @@
         };
       };
 
-      nixosConfigurations = {
-        ${hostname} = nixpkgs.lib.nixosSystem {
-          specialArgs = { inherit inputs outputs pkgs; };
-          modules = [
-            ./system/nixos
-            home-manager.nixosModules.home-manager
-            {
-              home-manager.useGlobalPkgs = true;
-              home-manager.useUserPackages = true;
-              home-manager.extraSpecialArgs = { inherit inputs outputs; };
-              home-manager.users.${username} = import ./home;
-            }
-          ];
-        };
+      nixosConfigurations = lib.mkSystem {
+        type = "nixos";
       };
 
-      darwinConfigurations = {
-        ${hostname} = inputs.nix-darwin.lib.darwinSystem {
-          specialArgs = { inherit inputs outputs pkgs; };
-          modules = [
-            ./system/darwin
-            home-manager.darwinModules.home-manager
-            {
-              home-manager.useGlobalPkgs = true;
-              # home-manager.useUserPackages = true;
-              home-manager.extraSpecialArgs = { inherit inputs outputs; };
-              home-manager.users.${username} = import ./home;
-            }
-          ];
-        };
+      darwinConfigurations = mkSystem {
+        type = "darwin";
       };
 
       # Convenience output that aggregates the outputs for home, nixos, and darwin configurations.
@@ -124,25 +104,25 @@
             (builtins.attrNames inputs.self.homeConfigurations)
             (attr: inputs.self.homeConfigurations.${attr}.activationPackage);
         in
-        nixtop // hometop;
-
-      checks.${system}.pre-commit-check = inputs.git-hooks.lib.${system}.run {
-        src = pkgs.lib.cleanSource ./.;
-
-        hooks = {
-          # TODO: treefmt, selene, shellcheck
-          editorconfig-checker.enable = true;
-          nixpkgs-fmt.enable = true;
-          stylua = {
-            enable = true;
-            entry = "${pkgs.stylua}/bin/stylua --config-path ./config/nvim/stylua.toml";
-          };
-        };
-      };
-
-      devShells.${system}.default = pkgs.mkShell {
-        inherit (self.checks.${system}.pre-commit-check) shellHook;
-        buildInputs = self.checks.${system}.pre-commit-check.enabledPackages;
-      };
+        nixtop // darwintop // hometop;
+
+      # checks.${system}.pre-commit-check = inputs.git-hooks.lib.${system}.run {
+      #   src = pkgs.lib.cleanSource ./.;
+      #
+      #   hooks = {
+      #     # TODO: treefmt, selene, shellcheck
+      #     editorconfig-checker.enable = true;
+      #     nixpkgs-fmt.enable = true;
+      #     stylua = {
+      #       enable = true;
+      #       entry = "${pkgs.stylua}/bin/stylua --config-path ./config/nvim/stylua.toml";
+      #     };
+      #   };
+      # };
+      #
+      # devShells.${system}.default = pkgs.mkShell {
+      #   inherit (self.checks.${system}.pre-commit-check) shellHook;
+      #   buildInputs = self.checks.${system}.pre-commit-check.enabledPackages;
+      # };
     };
 }
diff --git a/lib/default.nix b/lib/default.nix
index 1406aebe..7661923b 100644
--- a/lib/default.nix
+++ b/lib/default.nix
@@ -1,8 +1,62 @@
 { inputs, ... }:
+with inputs.nixpkgs.lib;
 let
   lockfile = builtins.fromJSON (builtins.readFile ../flake.lock);
   inherit (inputs.nixpkgs) lib;
+
+  dotfiles = import ../config.nix;
+
+  foreachSystem = genAttrs [ "x86_64-linux" "aarch64-darwin" ];
+
+  pkgsBySystem = foreachSystem (
+    system:
+    # https://github.com/nix-community/home-manager/issues/2942#issuecomment-1378627909
+    import inputs.nixpkgs {
+      inherit system;
+      config = {
+        allowUnfree = true;
+        allowUnfreePredicate = (_: true);
+        packageOverrides = pkgs: {
+          unstable = import inputs.nixpkgs-unstable {
+            inherit (pkgs) system config;
+          };
+        };
+      };
+    }
+  );
+
 in
 {
   stateVersion = "${builtins.elemAt (lib.splitString "-" lockfile.nodes.home-manager.original.ref) 1}";
+
+  mkSystem = { type }:
+    let
+      # TODO: assert type is either "darwin" or "nixos"
+      isDarwin = type == "darwin";
+      osConfig = ../system/${if isDarwin then "darwin" else "nixos" };
+      userHMConfig = ../home;
+
+      # NixOS vs nix-darwin functionst
+      systemFunc = if isDarwin then inputs.darwin.lib.darwinSystem else inputs.nixpkgs.lib.nixosSystem;
+      osModules = if isDarwin then inputs.home-manager.darwinModules else inputs.home-manager.nixosModules;
+
+      hostSystem = if isDarwin then dotfiles.darwin else dotfiles.nixos;
+      pkgs = pkgsBySystem.${hostSystem.system};
+    in
+    {
+      ${hostSystem.hostname} = systemFunc
+        {
+          specialArgs = { inherit inputs pkgs dotfiles; };
+          modules = [
+            osConfig
+            osModules.home-manager
+            {
+              home-manager.useGlobalPkgs = true;
+              # home-manager.useUserPackages = true;
+              home-manager.extraSpecialArgs = { inherit inputs dotfiles; };
+              home-manager.users.${dotfiles.home.username} = import userHMConfig;
+            }
+          ];
+        };
+    };
 }