feat: refactor flake.nix

systems/default.nix

@@ -0,0 +1,42 @@
+{
+  self,
+  inputs,
+  constants,
+}: let
+  lib = inputs.nixpkgs.lib;
+  vars = import ./vars.nix;
+
+  specialArgsForSystem = system:
+    {
+      inherit (constants) username userfullname useremail;
+      # use unstable branch for some packages to get the latest updates
+      pkgs-unstable = import inputs.nixpkgs-unstable {
+        inherit system; # refer the `system` parameter form outer scope recursively
+        # To use chrome, we need to allow the installation of non-free software
+        config.allowUnfree = true;
+      };
+    }
+    // inputs;
+
+  allSystemSpecialArgs = with constants; {
+    x64_system_specialArgs = specialArgsForSystem x64_system;
+    aarch64_system_specialArgs = specialArgsForSystem aarch64_system;
+    riscv64_system_specialArgs = specialArgsForSystem riscv64_system;
+
+    x64_darwin_specialArgs = specialArgsForSystem x64_darwin;
+    aarch64_darwin_specialArgs = specialArgsForSystem aarch64_darwin;
+  };
+
+  args = lib.attrsets.mergeAttrsList [
+    inputs
+    constants
+    vars
+    allSystemSpecialArgs
+    {inherit self;}
+  ];
+in
+  lib.attrsets.mergeAttrsList [
+    (import ./nixos.nix args)
+    (import ./darwin.nix args)
+    (import ./colmena.nix args)
+  ]