fibonacci_closure.go

/*
Exercise: Fibonacci closure
Let's have some fun with functions.

Implement a fibonacci function that returns a function (a closure) that returns successive fibonacci numbers (0, 1, 1, 2, 3, 5, ...).

https://tour.golang.org/moretypes/26
*/


package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func() int {
	m := make(map[int]int)
	m[0] = 0
	m[1] = 0
	return func() int {
		res := m[0] + m[1]
		m[0] = m[1]
		if res != 0 {
			m[1] = res
		} else {
			m[1] = 1
		}
		return res
	}
}

func main() {
	f := fibonacci()
	for i := 0; i < 10; i++ {
		fmt.Println(f())
	}
}