scala 函数也是类

在scala中有一个function1的trait,

@annotation.implicitNotFound(msg = "No implicit view available from ${T1} => ${R}.")
trait Function1[@specialized(scala.Int, scala.Long, scala.Float, scala.Double/*, scala.AnyRef*/) -T1, @specialized(scala.Unit, scala.Boolean, scala.Int, scala.Float, scala.Long, scala.Double/*, scala.AnyRef*/) +R] extends AnyRef { self =>
  /** Apply the body of this function to the argument.
   *  @return   the result of function application.
   */
  def apply(v1: T1): R

  /** Composes two instances of Function1 in a new Function1, with this function applied last.
   *
   *  @tparam   A   the type to which function `g` can be applied
   *  @param    g   a function A => T1
   *  @return       a new function `f` such that `f(x) == apply(g(x))`
   */
  @annotation.unspecialized def compose[A](g: A => T1): A => R = { x => apply(g(x)) }

  /** Composes two instances of Function1 in a new Function1, with this function applied first.
   *
   *  @tparam   A   the result type of function `g`
   *  @param    g   a function R => A
   *  @return       a new function `f` such that `f(x) == g(apply(x))`
   */
  @annotation.unspecialized def andThen[A](g: R => A): T1 => A = { x => g(apply(x)) }

  override def toString() = "<function1>"
}

 在scala 的shell中,定义一个函数f,如下,其实就是继承了Function1

同时,函数类也是可以被继承的.

object MyTest extends (Int=>Int){


  def apply(x:Int): Int ={
    println(x+1)
    x+1
  }


  def main(args: Array[String]) {
    val test = MyTest(1)

  }
  
}

输出2