fibonacci.go

//fib(0) = 0, fib(1) = 1, fib(n) = fib(n-1) + fib(n-2)
func fib() func() int {
	a, b := 0, 1

	return func() int {
		defer func() {
			a, b = b, a+b
		}()
		return a
	}
}

func main() {
	f := fib()
	// Function calls are evaluated left-to-right.
	for i := 0; i <= 4; i++ {
		fmt.Println(f())
	}
}