"A Tour of Go" http://tour.golang.org/#47

tour47.go

/*
 * http://tour.golang.org/#47
 * OR
 * http://http://go-tour-jp.appspot.com/#46
 */

package main

import (
	"fmt"
)

// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func() int {
	n, ok := 0, false
	a, b := 0, 0
	return func() int {
		var ret int = a + b
	
		if false != ok {
			if a > b {
				b += a
				ret = b
			} else {
				a += b
				ret = a
			}
		} else {
			ret = n
			n++
			if 1 < n {
				ok = true
				a = 1
			}
		}

		return ret
	}
}

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