use flake isntead of shell.nix

praktikum-5/flake.nix

@@ -0,0 +1,38 @@
+{
+  description = "Rechnerstrukturen Praktikum 5";
+
+  inputs = {
+    flake-parts.url = "github:hercules-ci/flake-parts";
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+  };
+
+  outputs = inputs @ {flake-parts, ...}:
+    flake-parts.lib.mkFlake {inherit inputs;} {
+      imports = [];
+      systems = ["x86_64-linux" "aarch64-linux" "aarch64-darwin" "x86_64-darwin"];
+      perSystem = {
+        config,
+        self',
+        inputs',
+        pkgs,
+        system,
+        ...
+      }:
+        with pkgs.lib; {
+          devShells.default = with pkgs;
+            mkShell {
+              packages = [
+                openjdk
+                ant
+              ];
+
+              shellHook = ''
+                echo "Usage Example:"
+                echo "ant run -Dmain-class=aufgabe3.Server"
+              '';
+            };
+        };
+      flake = {
+      };
+    };
+}