Implicit Resolution in Play Framework JSON Library

问题

Working with the Play Framework's JSON Library, I'm creating a Format[T] for some class T.

val a: JsPath = (JsPath \ "age")
val b: Format[Int] = (JsPath \ "age").format[Int]
val x: FunctionalBuilder[OFormat]#CanBuild2[Int, String] = ( 
           (JsPath \ "age").format[Int] and 
           (JsPath \ "location").format[String]
       )

Looking at the explicit types, we see that (in x) calling Format[Int] and Format[String] returns a type of FunctionalBuilder[OFormat]#CanBuild2[Int, String].

How does this conversion occur in the Play Framework JSON Library source?

来源：https://stackoverflow.com/questions/21964407/implicit-resolution-in-play-framework-json-library