type_class.scala

  trait Foo[T] {
    def bar(list: Seq[T]): Unit
  }
  object Foo {
    def bar[T: Foo](list: Seq[T]): Unit = implicitly[Foo[T]].bar(list)

    implicit val FooInt = new Foo[Int] {
      def bar(list: Seq[Int]): Unit = println("Int " + list)
    }
    implicit val FooDouble = new Foo[Double] {
      def bar(list: Seq[Double]): Unit = println("Double " + list)
    }
    implicit val FooFloat = new Foo[Float] {
      def bar(list: Seq[Float]): Unit = println("Float " + list)
    }
    implicit val FooString = new Foo[String] {
      def bar(list: Seq[String]): Unit = println("String " + list)
    }
  }

  Foo.bar(Seq(1))
  Foo.bar(Seq(1d))
  Foo.bar(Seq(1f))
  Foo.bar(Seq("1"))