Function update

packages/core/primitives/signals/src/signal.ts:71–71

(updateFn: (value: T) => T)

  runPostProducerCreatedFn(node);
  const set = (newValue: T) => signalSetFn(node, newValue);
  const update = (updateFn: (value: T) => T) => signalUpdateFn(node, updateFn);
  return [getter, set, update];
}