Golang : How to make function callback or pass value from function as parameter?

There are times we need to evaluate a function and pass the evaluated value as parameter to a function. In Golang, this is known as function callback. Below is an example of function callback in action.

 package main

 import "fmt"

 func square(f func(int) int, x int) int {
 return f(x * x)
 }

 func main() {

 // call back functions for 2 times
 fmt.Printf("%v\n", square(func(i int) int {
 return i * i
 }, 2))

 }

Sample output :

16

Reference :

https://www.socketloop.com/tutorials/golang-squaring-elements-in-array