ex3

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Exercise 3

Question

Write a function called prefixer that has an input parameter of type +string+ and returns a function that has an input parameter of type string and returns a string. The returned function should prefix its input with the string passed into prefixer. Use the following main function to test prefixer:

func main() {
    helloPrefix := prefixer("Hello")
    fmt.Println(helloPrefix("Bob")) // should print Hello Bob
    fmt.Println(helloPrefix("Maria")) // should print Hello Maria
}

Solution

The prefixer function looks like this:

func prefixer(prefix string) func(string) string {
    return func (body string) string {
        return prefix + " " + body
    }
}

The return type is a function signature, which has the keyword func, the input parameter for the returned function ((string)) and the return type for the returned function (string). In the body of the function, you return an anonymous function. This function is a closure; it refers to the prefix input parameter to prefixer.