gistfile1.txt

object CoolStuff {
    implicit class StringImplicits(s: String) {
        def withCool(s2: String): String = s + " COOL " + s2
    }

    implicit class SeqStringImplicits(strings: Seq[String]) {
        def joinEm(sep: String = " | "): String = {
            // error: not found: value withCool
            strings.map(withCool).mkString(sep)
            // But this will work:
            // strings.map(s => StringImplicits(s).withCool).mkString(sep)
        }
    }
}