the-way-to-go_ZH_CN/eBook/exercises/chapter_6/fibonacci_closure.go

package main

// fib returns a function that returns
// successive Fibonacci numbers.
func fib() func() int {
	a, b := 1, 1
	return func() int {
		a, b = b, a+b
		return b
	}
}

func main() {
	f := fib()
	// Function calls are evaluated left-to-right.
	// println(f(), f(), f(), f(), f())
	for i := 0; i <= 9; i++ {
		println(i+2, f())
	}
}