Go Tour: Exercise: Exercise: Fibonacci closure - My solution

gistfile1.go

package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func() int {
	a := 0
	b := 1
	f := func() int {
		s := a
		a = b
		b = s + b
		
		return s
	}
	
	return f
}

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

var s is unneccessary
a, b := 0, 1
return func() int {
a = a + b
a, b = b, a
return a
}

var s is necessary, the first element of the Fibonacci sequence is 0 so you need to stash a somewhere before you modify it.

var s is unneccessary，but a, b have to initialize as -1, 1

func fibonoacci() func() int {
a, b := -1, 1
return func() int {
a, b = b, a+b
return b
}
}