diff --git a/.gitmodules b/.gitmodules
index c162f9a..2564576 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -13,3 +13,6 @@
 [submodule "cs4212/hw3-llvmlite-flavourtown"]
 	path = cs4212/hw3-llvmlite-flavourtown
 	url = https://github.com/cs4212/hw3-llvmlite-flavourtown
+[submodule "cs4212/hw4-oat-favourtown"]
+	path = cs4212/hw4-oat-favourtown
+	url = https://github.com/cs4212/hw4-oat-favourtown
diff --git a/cs4212/hw3-llvmlite-flavourtown b/cs4212/hw3-llvmlite-flavourtown
index b0efc2f..9d76411 160000
--- a/cs4212/hw3-llvmlite-flavourtown
+++ b/cs4212/hw3-llvmlite-flavourtown
@@ -1 +1 @@
-Subproject commit b0efc2f6f1fb6a107aace155e1fb6a1b2fa3f729
+Subproject commit 9d764118bfa68707a0482d86097d5b94cece45e7
diff --git a/cs4212/hw4-oat-favourtown b/cs4212/hw4-oat-favourtown
new file mode 160000
index 0000000..7696613
--- /dev/null
+++ b/cs4212/hw4-oat-favourtown
@@ -0,0 +1 @@
+Subproject commit 7696613d43a2e9b71e3185321dac74b2bebd9720
diff --git a/devenv.lock b/devenv.lock
deleted file mode 100644
index 4d958ed..0000000
--- a/devenv.lock
+++ /dev/null
@@ -1,103 +0,0 @@
-{
-  "nodes": {
-    "devenv": {
-      "locked": {
-        "dir": "src/modules",
-        "lastModified": 1754141078,
-        "owner": "cachix",
-        "repo": "devenv",
-        "rev": "a21413b7977726581d26951da25d4c31235c3253",
-        "type": "github"
-      },
-      "original": {
-        "dir": "src/modules",
-        "owner": "cachix",
-        "repo": "devenv",
-        "type": "github"
-      }
-    },
-    "flake-compat": {
-      "flake": false,
-      "locked": {
-        "lastModified": 1747046372,
-        "owner": "edolstra",
-        "repo": "flake-compat",
-        "rev": "9100a0f413b0c601e0533d1d94ffd501ce2e7885",
-        "type": "github"
-      },
-      "original": {
-        "owner": "edolstra",
-        "repo": "flake-compat",
-        "type": "github"
-      }
-    },
-    "git-hooks": {
-      "inputs": {
-        "flake-compat": "flake-compat",
-        "gitignore": "gitignore",
-        "nixpkgs": [
-          "nixpkgs"
-        ]
-      },
-      "locked": {
-        "lastModified": 1750779888,
-        "owner": "cachix",
-        "repo": "git-hooks.nix",
-        "rev": "16ec914f6fb6f599ce988427d9d94efddf25fe6d",
-        "type": "github"
-      },
-      "original": {
-        "owner": "cachix",
-        "repo": "git-hooks.nix",
-        "type": "github"
-      }
-    },
-    "gitignore": {
-      "inputs": {
-        "nixpkgs": [
-          "git-hooks",
-          "nixpkgs"
-        ]
-      },
-      "locked": {
-        "lastModified": 1709087332,
-        "owner": "hercules-ci",
-        "repo": "gitignore.nix",
-        "rev": "637db329424fd7e46cf4185293b9cc8c88c95394",
-        "type": "github"
-      },
-      "original": {
-        "owner": "hercules-ci",
-        "repo": "gitignore.nix",
-        "type": "github"
-      }
-    },
-    "nixpkgs": {
-      "locked": {
-        "lastModified": 1753719760,
-        "owner": "cachix",
-        "repo": "devenv-nixpkgs",
-        "rev": "0f871fffdc0e5852ec25af99ea5f09ca7be9b632",
-        "type": "github"
-      },
-      "original": {
-        "owner": "cachix",
-        "ref": "rolling",
-        "repo": "devenv-nixpkgs",
-        "type": "github"
-      }
-    },
-    "root": {
-      "inputs": {
-        "devenv": "devenv",
-        "git-hooks": "git-hooks",
-        "nixpkgs": "nixpkgs",
-        "pre-commit-hooks": [
-          "git-hooks"
-        ]
-      }
-    }
-  },
-  "root": "root",
-  "version": 7
-}
diff --git a/devenv.nix b/devenv.nix
deleted file mode 100644
index 822a1ae..0000000
--- a/devenv.nix
+++ /dev/null
@@ -1,5 +0,0 @@
-{ pkgs, lib, config, inputs, ... }:
-
-{
-  packages = [ pkgs.git pkgs.opam pkgs.typst ];
-}
diff --git a/devenv.yaml b/devenv.yaml
deleted file mode 100644
index 116a2ad..0000000
--- a/devenv.yaml
+++ /dev/null
@@ -1,15 +0,0 @@
-# yaml-language-server: $schema=https://devenv.sh/devenv.schema.json
-inputs:
-  nixpkgs:
-    url: github:cachix/devenv-nixpkgs/rolling
-
-# If you're using non-OSS software, you can set allowUnfree to true.
-# allowUnfree: true
-
-# If you're willing to use a package that's vulnerable
-# permittedInsecurePackages:
-#  - "openssl-1.1.1w"
-
-# If you have more than one devenv you can merge them
-#imports:
-# - ./backend
diff --git a/flake.lock b/flake.lock
new file mode 100644
index 0000000..7bc63f8
--- /dev/null
+++ b/flake.lock
@@ -0,0 +1,61 @@
+{
+  "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1759826507,
+        "narHash": "sha256-vwXL9H5zDHEQA0oFpww2one0/hkwnPAjc47LRph6d0I=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "bce5fe2bb998488d8e7e7856315f90496723793c",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/flake.nix b/flake.nix
new file mode 100644
index 0000000..2706c93
--- /dev/null
+++ b/flake.nix
@@ -0,0 +1,34 @@
+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    flake-utils = {
+      url = "github:numtide/flake-utils";
+    };
+  };
+
+  outputs =
+    {
+      flake-utils,
+      nixpkgs,
+      ...
+    }:
+    flake-utils.lib.eachDefaultSystem (
+      system:
+      let
+        pkgs = import nixpkgs {
+          inherit system;
+        };
+      in
+      {
+        devShells.default = pkgs.mkShell {
+          buildInputs = [
+            pkgs.git
+            pkgs.opam
+            pkgs.typst
+            pkgs.gmp
+            pkgs.pkgconf
+          ];
+        };
+      }
+    );
+}