Fixed nixpkgs by generating a function by system.

flake.nix

@@ -3,33 +3,39 @@
 
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
   };
 
-  outputs = { self, nixpkgs }: {
-    writePythonApplication = {name, contentFile}: let
-          wrappedScript = pkgs.writeText "wrappedScript" (builtins.readFile contentFile);
-          in
-          pkgs.writeShellApplication {
-          name = name;
-          runtimeInputs = [
-              wrappedScript
-              pkgs.python311];
-          text = ''
-              exec ${pkgs.python38}/bin/python ${wrappedScript} "$@"
-          '';
-          };
+  outputs = { self, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = import nixpkgs { inherit system;};
+      in
+    {
+      writePythonApplication = {name, contentFile}: let
+            wrappedScript = pkgs.writeText "wrappedScript" (builtins.readFile contentFile);
+            in
+            pkgs.writeShellApplication {
+            name = name;
+            runtimeInputs = [
+                wrappedScript
+                pkgs.python311];
+            text = ''
+                exec ${pkgs.python38}/bin/python ${wrappedScript} "$@"
+            '';
+            };
 
-      writeBabashkaApplication = {name, contentFile}: let
-          wrappedScript = pkgs.writeText "wrappedScript" (builtins.readFile contentFile);
-          in
-          pkgs.writeShellApplication {
-          name = name;
-          runtimeInputs = [
-              wrappedScript
-              pkgs.babashka];
-          text = ''
-              exec ${pkgs.babashka}/bin/bb ${wrappedScript} "$@"
-          '';
-          };
-  };
+        writeBabashkaApplication = {name, contentFile}: let
+            wrappedScript = pkgs.writeText "wrappedScript" (builtins.readFile contentFile);
+            in
+            pkgs.writeShellApplication {
+            name = name;
+            runtimeInputs = [
+                wrappedScript
+                pkgs.babashka];
+            text = ''
+                exec ${pkgs.babashka}/bin/bb ${wrappedScript} "$@"
+            '';
+            };
+    });
 }