A simple typeclass sample

TypeClasses.scala

object TypeClasses {
  // the trait defined independent of thing(type A) & evidence(type CanFoo[A])
  trait CanFoo[A] {
    def foos(x: A): String
  }

  // object defined whose apply method takes an implicit param of type CanFoo[A]
  object CanFoo {
    def apply[A:CanFoo]: CanFoo[A] = implicitly
  }

  // A is of type Wrapper i.e. thing
  case class Wrapper(wrapped: String)

  // implicit object or evidence
  // implicit ensures that there is "only" one object which extends CanFoo[Wrapper]
  implicit object WrapperCanFoo extends CanFoo[Wrapper] {
    def foos(x: Wrapper) = x.wrapped
  }

  // test method
  def foo[A:CanFoo](thing: A) = CanFoo[A].foos(thing)

  def main(args: Array[String]): Unit = {
    println(foo(Wrapper("sbcd90")))
  }
}