small example of polymorphic encoders

encoder.scala

trait Encoder[From] {
  type To
  def encode(from: From): To
}
object Encoder {
  type Aux[From, To0] = Encoder[From] {
    type To = To0
  }
  implicit def compose[A, B, C](implicit e1: Encoder.Aux[A, B], e2: Encoder.Aux[B, C]): Encoder.Aux[A, C] =
    new Encoder[A] {
      type To = C
      override def encode(from: A): C = e2.encode(e1.encode(from))
    }
  implicit val intToBooleanEncoder = new Encoder[Int] {
    type To = Boolean
    override def encode(from: Int): Boolean = true
  }
  implicit val booleanToStringEncoder = new Encoder[Boolean] {
    type To = String
    override def encode(from: Boolean): String = "hello"
  }
}
def print[T, R](t: T)(implicit p: Encoder.Aux[T, R]): R = p.encode(t)
print(10) // true
print(true) // hello
print[Int, String](10) // hello