Go Tour Exercise on Closures - a Fibonacci sequence generator - http://tour.golang.org/moretypes/22

fibonacci-closure.go

package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func() int {
	seq := []int{0,1}
	i := 0
	return func() int {
		seq = append(seq, seq[i] + seq[i + 1])
		i++
		return seq[i - 1]
	}
}

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