Anonymous function in Go Language

Go language provides a special feature known as an anonymous function. An anonymous function is a function which doesn’t contain any name. It is useful when you want to create an inline function. In Go language, an anonymous function can form a closure. An anonymous function is also known as function literal.

Syntax:

func(parameter_list)(return_type){
// code..

// Use return statement if return_type are given
// if return_type is not given, then do not 
// use return statement
return
}()

Example:

// Go program to illustrate how
// to create an anonymous function
package main

import "fmt"

func main() {

    // Anonymous function
   func(){

      fmt.Println("Welcome! to GeeksforGeeks")
  }()

}

Output:

Welcome! to GeeksforGeeks

Important Points:

• In Go language, you are allowed to assign an anonymous function to a variable. When you assign a function to a variable, then the type of the variable is of function type and you can call that variable like a function call as shown in the below example.

  Example:

  // Go program to illustrate
  // use of an anonymous function
  package main
  
  import "fmt"
  
  func main() {
  
      // Assigning an anonymous
     // function to a variable
     value := func(){
        fmt.Println("Welcome! to GeeksforGeeks")
    }
    value()
  
  }

  Output:

  Welcome! to GeeksforGeeks

• You can also pass arguments in the anonymous function.

  Example:

  // Go program to pass arguments
  // in the anonymous function
  package main
  
  import "fmt"
  
  func main() {
  
      // Passing arguments in anonymous function
    func(ele string){
        fmt.Println(ele)
    }("GeeksforGeeks")
  
  }

  Output:

  GeeksforGeeks

• You can also pass an anonymous function as an argument into other function.

  Example:

  // Go program to pass an anonymous
  // function as an argument into
  // other function
  package main
  
  import "fmt"
  
  
    // Passing anonymous function
   // as an argument
   func GFG(i func(p, q string)string){
       fmt.Println(i ("Geeks", "for"))
  
   }
  
  func main() {
      value:= func(p, q string) string{
          return p + q + "Geeks"
      }
      GFG(value)
  }

  Output:

  GeeksforGeeks

• You can also return an anonymous function from another function.

  Example:

  // Go program to illustrate
  // use of anonymous function
  package main
  
  import "fmt"
  
   // Returning anonymous function
   func GFG() func(i, j string) string{
       myf := func(i, j string)string{
            return i + j + "GeeksforGeeks"
       }
      return myf
   }
  
  func main() {
      value := GFG()
      fmt.Println(value("Welcome ", "to "))
  }

  Output:

  Welcome to GeeksforGeeks