Closure in Golang

A closure shares its state across calls.

The following code implements the Fibonacci series from Tour of Go.

https://tour.golang.org/moretypes/26

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

The interesting thing to note is that function f is sharing its state across calls.

the state constitutes first and second .

On each call of the closure, the previous values of the variables are available.