1 files changed, 16 insertions, 0 deletions
diff --git a/src/util.ts b/src/util.ts
new file mode 100644
index 0000000..f6420b9
--- /dev/null
+++ b/src/util.ts
@@ -0,0 +1,16 @@
+export class MutableValue<T> {
+    private inner: T;
+
+    constructor(inner: T) {
+        this.inner = inner;
+    }
+
+    get value() {
+        return this.inner
+    }
+
+    public deriveNew(mutator: (self: T) => T): MutableValue<T> {
+        this.inner = mutator(this.inner);
+        return new MutableValue(this.inner);
+    }
+}