diff --git a/package.json b/package.json
index 50a6587..8402d8d 100644
--- a/package.json
+++ b/package.json
@@ -18,6 +18,16 @@
         "types": "./dist/lib.d.cts",
         "default": "./dist/lib.cjs"
       }
+    },
+    "./util": {
+      "import": {
+        "types": "./dist/util.d.mts",
+        "default": "./dist/util.mjs"
+      },
+      "require": {
+        "types": "./dist/util.d.cts",
+        "default": "./dist/util.cjs"
+      }
     }
   },
   "scripts": {
diff --git a/rollup.config.ts b/rollup.config.ts
index 22d5101..67c2c78 100644
--- a/rollup.config.ts
+++ b/rollup.config.ts
@@ -5,30 +5,40 @@ import ts from "rollup-plugin-ts"
 import pkg from "./package.json" assert { type: "json" }
 
 
-export default defineConfig({
-    input: "src/lib.ts",
+export const createBundleConfig = (
+    input:  string,
+    name:   keyof typeof pkg.exports,
+) => (
+    defineConfig({
+        input,
 
-    output: [
-        {
-            file:    pkg.exports["."].import.default,
-            format:  "esm",
-        },
+        output: [
+            {
+                file:    pkg.exports[name].import.default,
+                format:  "esm",
+            },
+            {
+                file:    pkg.exports[name].require.default,
+                format:  "cjs",
+            },
+        ],
 
-        {
-            file:    pkg.exports["."].require.default,
-            format:  "cjs",
-        },
-    ],
+        external: id => !/^[./]/.test(id),
 
-    external: id => !/^[./]/.test(id),
+        plugins: [
+            nodeResolve(),
+            ts(),
 
-    plugins: [
-        nodeResolve(),
-        ts(),
+            cleanup({
+                comments: "jsdoc",
+                extensions: ["ts"],
+            }),
+        ],
+    })
+)
 
-        cleanup({
-            comments: "jsdoc",
-            extensions: ["ts"],
-        }),
-    ],
-})
+
+export default [
+    createBundleConfig("src/lib.ts", "."),
+    createBundleConfig("src/util/lib.ts", "./util"),
+]
diff --git a/src/lib.ts b/src/lib.ts
index c929b01..0f31a88 100644
--- a/src/lib.ts
+++ b/src/lib.ts
@@ -1,5 +1,6 @@
 export {
     abstract, expression, trait,
+    type Implements,
     type Trait,
     type TraitExpression
 } from "."
diff --git a/src/util/lib.ts b/src/util/lib.ts
new file mode 100644
index 0000000..4e2038a
--- /dev/null
+++ b/src/util/lib.ts
@@ -0,0 +1,6 @@
+export {
+    Extend,
+    ExtendFn,
+    Extendable,
+    ExtendableFn
+} from "."