"A Tour of Go"

fibonacci.go

/*
Exercise: Fibonacci closure

Let's have some fun with functions.
Implement a fibonacci function that returns a function (a closure) that returns successive fibonacci numbers.
*/
package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func() int {
    f0,f1,fn := 0,1,0
    
    return func() int {
        fn = f0+f1
        f0 = f1
        f1 = fn
        
        return fn
    }
}

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