An example of Groovy's `@Memoized` feature for automatically caching function results. From the video at World of Zero: https://youtu.be/90YDpzoeGEk

MemoizedFibonacci.groovy

package com.worldofzero.example

import groovy.transform.Memoized

import java.util.concurrent.TimeUnit

/**
 * An example use of Memoizing in Groovy
 * World of Zero {@link youtube.com/worldofzerodevelopment}
 */
class Application {
    static void main(String... args) {
        int iterations = 20
        long startTime = System.nanoTime()
        for(int i = 0; i < iterations; ++i) {
            System.out.println(fib(30))
        }
        long endTime = System.nanoTime()
        long differenceTime = TimeUnit.MILLISECONDS.convert(endTime - startTime, TimeUnit.NANOSECONDS)
        System.out.println("Time taken $differenceTime ms")
    }

    @Memoized
    static int fib(int n) {
        switch(n) {
            case 0:
                return 0
            case 1:
                return 1
            default:
                if (n < 0) {
                    return 0
                } else {
                    return fib(n - 1) + fib(n - 2)
                }
        }
    }
}