How to implement undo and redo operations

Undo and Redo operations can be implemented with the help of 2 stacks.

• Push all operations to Undo stack.
• When undo is called, pop operations from Undo stack and push it to Redo stack.
• When redo is called, pop operations from Redo stack and push it to Undo stack.

package main
import (
 "fmt"
)
type stack []string
var undoStack *stack
var redoStack *stack
func (s *stack) isEmpty() bool {
 return len(*s) == 0
}
func (s *stack) push(val string) {
 *s = append(*s, val)
 fmt.Println("Pushed : ", val)
}
func (s *stack) pop() (string, bool) {
 if s.isEmpty() {
  return "", false
 }
 lstIdx := len(*s) - 1
 top := (*s)[lstIdx]
 *s = (*s)[:lstIdx]
 return top, true
}
func undo() {
 if val, ok := undoStack.pop(); ok {
  redoStack.push(val)
  fmt.Printf("\nchanges for %s undone\n", val)
 }
}
func redo() {
 if val, ok := redoStack.pop(); ok {
  undoStack.push(val)
  fmt.Printf("\nchanges for %s reverted\n", val)
 }
}
func main() {
 undoStack = new(stack)
 redoStack = new(stack)
 undoStack.push("World")
 undoStack.push("is")
 undoStack.push("beautiful")
 undoStack.push("Hello")
 undoStack.push("Listener")
 undo()
 undo()
 redo()
 redo()
}