Tail recursive Fibonacci

Fibonacci

package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func() int {
    a1 := 0
    a2 := 1
    return func() int {
        a1, a2 = fib(a1, a2)
        return a2
    }
}

func fib(a1 int, a2 int) (int, int) {
    return a2, a1 + a2
}

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