Overview

Higher-order functions are those functions that either accept a function as a type or return function. Since a function is a first-order variable in Golang they can be passed around and also returned from some function and assigned to a variable.

Code:

In below Example 1

• print function takes a function of type func(int, int) int as an argument

• getAreafunc returns a function of type func(int, int) int

Example 1

package main
import "fmt"
func main() {
areaF := getAreaFunc()
print(3, 4, areaF)
}
func print(x, y int, area func(int, int) int) {
fmt.Printf("Area is: %d\n", area(x, y))
}
func getAreaFunc() func(int, int) int {
return func(x, y int) int {
return x * y
}
}

Output:

12

Example 2:

Let’s see one more little complex example where

• Two functions are passed as an argument
• Two functions are returned from a function

package main
import "fmt"
func main() {
add, subtract := getAddSubtract()
print(3, 4, add, subtract)
}
func print(x, y int, add func(int, int) int, subtract func(int, int) int) {
fmt.Printf("Sum is: %d\n", add(x, y))
fmt.Printf("Difference Value is: %d\n", subtract(x, y))
}
func getAddSubtract() (func(int, int) int, func(int, int) int) {
add := func(x, y int) int {
return x + y
}
subtract := func(x, y int) int {
return x - y
}
return add, subtract
}

Output:

Sum is: 7
Difference Value is: 1