Lazy Fibonacci implementation in Java using the Functional Java library.

FunctionalJavaFibonacci.java

import fj.F2;
import fj.data.List;
import fj.data.Stream;

public class FunctionalJavaFibonacci {
	
	public static final Stream<Long> fibonacciSequence = new F2<Long, Long, Stream<Long>>() {
	      public Stream<Long> f(final Long a, final Long b) {
	        return Stream.cons(a, curry().f(b).lazy().f(a + b));
	      }
	 }.f(0L, 1L);

	 public static void main(String[] args) {
		List<Long> fibonacciUpto25 = fibonacciSequence.take(25).toList();
		System.out.println(fibonacciUpto25);
	}
}