Explain the use of Go's anonymous functions for code reuse?

In Go, anonymous functions are functions without a name. They are also known as lambda functions or closures. Anonymous functions are a powerful feature of the language, and they are commonly used for code reuse and encapsulation of functionality.

One of the main benefits of using anonymous functions is that they allow you to write code that is reusable in multiple contexts without having to define a named function. This can be especially useful when you need to pass a function as an argument to another function, or when you need to return a function as a value from a function.

Here's an example of an anonymous function that adds two integers:

sum := func(a, b int) int {
    return a + b
}

result := sum(3, 4) // result is 7

In this example, we define an anonymous function called **sum** that takes two integers as arguments and returns their sum. We then call the function with arguments 3 and 4, and store the result in a variable called **result**.

Anonymous functions can also capture variables from their surrounding context. This means that they can access and modify variables that are defined outside of their own scope. Here's an example:

func counter() func() int {
    i := 0
    return func() int {
        i++
        return i
    }
}

c := counter()
fmt.Println(c()) // prints 1
fmt.Println(c()) // prints 2
fmt.Println(c()) // prints 3

In this example, we define a function called **counter** that returns an anonymous function that increments and returns a counter variable **i**. We then call **counter** to create a new counter function **c**, and call it three times to print the values 1, 2, and 3.

Anonymous functions can also be used as closures to create function factories. For example, you could create a factory that generates custom sorting functions:

func sortFactory(order string) func([]int) []int {
    if order == "asc" {
        return func(a []int) []int {
            sort.Ints(a)
            return a
        }
    } else if order == "desc" {
        return func(a []int) []int {
            sort.Sort(sort.Reverse(sort.IntSlice(a)))
            return a
        }
    } else {
        panic("Unknown sort order")
    }
}

ascSort := sortFactory("asc")
descSort := sortFactory("desc")

numbers := []int{3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5}
fmt.Println(ascSort(numbers)) // prints [1 1 2 3 3 4 5 5 5 6 9]
fmt.Println(descSort(numbers)) // prints [9 6 5 5 5 4 3 3 2 1 1]

In this example, we define a **sortFactory** function that returns an anonymous function that sorts an array of integers in either ascending or descending order. We then call **sortFactory** to create two new sorting functions, **ascSort** and **descSort**, and use them to sort an array of numbers in ascending and descending order, respectively.

Overall, anonymous functions are a powerful and flexible feature of Go that allow you to write reusable code and create function factories that can generate custom functions on-the-fly.