How to recursively join a string to an array of type string in golang

There is already Join function in strings module. But it's not recursive, if you need recursive you can make it like this:

package main

import "fmt"

func join_helper(splitter string, arrOfStrings []string, res string) string {
    if len(arrOfStrings) == 0 {
       return res
    }

    if len(arrOfStrings) == 1 {
       return join_helper(splitter, arrOfStrings[1:], res + arrOfStrings[0])
    }

    return join_helper(splitter, arrOfStrings[1:], res + arrOfStrings[0] + splitter)
}

func join(splitter string, arrOfStrings []string) string {
    return join_helper(splitter, arrOfStrings, "")
}

func main(){
    fmt.Println(join(",", []string{"a", "b", "c", "d"}))
}

Something like this

package main

import (
    "fmt"
    "strings"
)

func flatJoin(sep string, args ...interface{}) string {
    values := make([]string, 0)
    for _, item := range args {
        switch v := item.(type) {
        case string:
            values = append(values, v)

        case []string:
            values = append(values, v...)
        case fmt.Stringer:
            values = append(values, v.String())
        default:
            values = append(values, fmt.Sprintf("%v", v))
        }
    }

    return strings.Join(values, sep)

}

func main() {
    fmt.Println(flatJoin(", ", "basic", "other", []string{"here", "more", "inner"}))
}

http://play.golang.org/p/yY6YnZZAak

This supports only one level of flattening, but you can customize the recursion on your switch statement depending on what you are expecting.