package coffee.liz.lambda.eval;

import lombok.RequiredArgsConstructor;

import java.util.function.Supplier;

/**
 * A memoizing thunk for lazy evaluation.
 * 
 * @param <T>
 *            Thunk type
 */
@RequiredArgsConstructor
public final class Thunk<T> implements Supplier<T> {
	private final Supplier<T> thinker; // https://www.youtube.com/shorts/Dzksib8YxSY
	private T cached = null;
	private boolean evaluated = false;

	@Override
	public T get() {
		if (!evaluated) {
			cached = thinker.get();
			evaluated = true;
		}
		return cached;
	}
}