public class MemoFunction<T, U> implements Function<T, U> {

	public final Map<T, U> cache = new ConcurrentHashMap<>();
	private final Function<T, U> function;

	public MemoFunction(Function<T, U> function) {
		this.function = function;
	}

	public Function<T, U> cache() {
		return input -> cache.computeIfAbsent(input, function::apply);
	}

	@Override
	public U apply(T t) {
		return function.apply(t);
	}
}