Solution for the fib exercise on the Go language tour.

fib.go

package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func() int {
	last := 0
	cur := 1
	count := 0
	return func() int {
		switch count {
			case 0:
				count += 1
				return last
			case 1:
				count += 1
				return cur
		}
		cur, last = last+cur, cur
		return cur
	}
}

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