scala type class
Encode the Expression Problem in Scala 2.x
(from: https://scalac.io/blog/typeclasses-in-scala/):
trait Show[A] {
def show(a: A): String
}
object Show {
def apply[A](implicit sh: Show[A]): Show[A] = sh
//needed only if we want to support notation: show(...)
def show[A: Show](a: A) = Show[A].show(a)
implicit class ShowOps[A: Show](a: A) {
def show = Show[A].show(a)
}
//type class instances
implicit val intCanShow: Show[Int] =
int => s"int $int"
implicit val stringCanShow: Show[String] =
str => s"string $str"
}