Implement a fibonacci function that returns a function (a closure) that returns successive fibonacci numbers.

go_tour_ex4_closure_fib.go

package main
 
import "fmt"
 
// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func() int {
    f1, f2 := 0, 1
    return func() int {
        f1, f2 = f2, f1 + f2
        return f1
    }
}
 
func main() {
    f := fibonacci()
    for i := 0; i < 10; i++ {
        fmt.Println(f())
    }
}