Tour of Golang | Exercise: Fibonacci closure - https://tour.golang.org/moretypes/26

FibonacciClosure.go

package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func() int {
	a, b := 0, 1
	return func() int {
		a, b = b, a+b     
    //This works because first RHS is computed and stored and then assigned to LHS, 
    //'a' doesn't changes value before b = a+b
		return b - a
	}
}

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


/*
OUTPUT:
0
1
1
2
3
5
8
13
21
34
*/