(no subject)

Provide an alternate implementation of the following class (a thunk) that uses no conditional logic.
For extra credit, make it thread-safe.

abstract class Thunk<T> {
  private boolean evaluated = false;
  private T value;
  public T get() {
    if (!evaluated) {
      value = compute();
      evaluated = true;
    }
    return value;
  }
  abstract protected T compute();
}