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I have seen a function named implicitly used in Scala examples. What is it, and how is it used? Example here : scala> sealed trait Foo[T] { def apply(list : List[T]) : Unit }; object Foo { | implicit def stringImpl = new Foo[String] { | def apply(list : List[String]) = println("String") | } | implicit def intImpl = new Foo[Int] { | def apply(list : List[Int]) = println("Int") | } | } ; def foo[A : Foo](x : List[A]) = implicitly[Foo[A]].apply(x) defined trait Foo defined module Foo foo: [A](x: List[A])(implicit evidence$1: Foo[A])Unit scala> foo(1) <console>:8: error: type mismatch; found : Int(1) required: List[?] foo(1) ^ scala> foo(List(1,2,3)) Int scala> foo(List("a","b","c")) String scala> foo(List(1.0)) <console>:8: error: could not find implicit value for evidence parameter of type Foo[Double] foo(List(1.0)) ^ Note that we have to write implicitly[Foo[A]].apply(x) since the compiler thinks that implicitly[Foo[A]](x) means that we call implicitly with parameters. Also see How to investigate objects/types/etc. from Scala REPL? and Where does Scala look for implicits?

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