golang-closures-anonymous-functions.md

Title: Golang: Passing anonymous functions and closures Tags: golang

Golang can pass functions to other functions.

This anonymous function takes in a string and returns a string. It is passed to another function.

	anon := func(s name) string {
		return "Hiya, " + name
	}
	anotherFunction(anon)

The other function looks like this. Note it defines the function signature it will accept

	func anotherFunction(f func(string) string) {
		result := f("David")
		fmt.Println(result) // Prints "Hiya, David"
	}

You can make the anonymous function close over a value, making it a closure.

Say the first anonymous function was like this.

	valueToCloseOver := "My name is HAL."
	anon := func(s name) string {
		return "Hiya, " + name + ". " + valueToCloseOver
	}
	anotherFunction(anon)

Regardless of where the anonymous function is passed to, it will always have access to 'valueToCloseOver'.

This example is trivial. But passing logic and state around is a powerful coding mechanism.