Scala/Play 入門者向けセッション #ScalaMatsuri

implicit関係 implicitパラメータ(暗黙)

scala> def f[A](implicit a: A) String = a.toString
<console>:1: error: '=' expected but identifier found.
       def f[A](implicit a: A) String = a.toString
                               ^

scala> def f[A](implicit a: A): String = a.toString
f: [A](implicit a: A)String

scala> f[Int]
res0: String = 1000

scala> f[String]
<console>:10: error: could not find implicit value for parameter a: String
              f[String]
               ^

scala> implicit val bbb: String = "foo"
bbb: String = foo

scala> f[String]
res2: String = foo