traits.scala

trait Printer {
  def print(what: String)
}

object Printer {
  object Stdout extends Printer {
    def print(what: String) = println(what)
  }

  def apply(writer: Writer): Printer = new Printer {
    def print(what: String) = writer.write(what)
  }

  def logger(logger: Logger): Printer = new Printer {
    def print(what: String) = logger.info(what)
  }
}

Printer.Stdout.print("poo")

Printer(System.out).print("pee")

val logger = // ...
Printer.logger(logger).print("fart")