3.隐式转换

1.scala中的类继承层次结构

2.Predef对象

下面是Predef的部分隐式转换源码：

scala> :implicits -v
/* 78 implicit members imported from scala.Predef */
  /* 48 inherited from scala.Predef */
  implicit def any2ArrowAssoc[A](x: A): ArrowAssoc[A]
  implicit def any2Ensuring[A](x: A): Ensuring[A]
  implicit def any2stringadd(x: Any): runtime.StringAdd
  implicit def any2stringfmt(x: Any): runtime.StringFormat
  implicit def boolean2BooleanConflict(x: Boolean): Object
  implicit def byte2ByteConflict(x: Byte): Object
  implicit def char2CharacterConflict(x: Char): Object
  implicit def double2DoubleConflict(x: Double): Object
  implicit def float2FloatConflict(x: Float): Object
  implicit def int2IntegerConflict(x: Int): Object
  implicit def long2LongConflict(x: Long): Object
  implicit def short2ShortConflict(x: Short): Object

 //....................