deltamaster posted @ Jun 17, 2014 10:22:10 PM in Scala with tags scala 函数 泛型 Functional Programming Liskov 协变 逆变 , 9114 阅读



trait Function1[-T, +U] {
  def apply(x: T): U



  • C[+T]:如果A是B的子类,那么C[A]是C[B]的子类。
  • C[-T]:如果A是B的子类,那么C[B]是C[A]的子类。
  • C[T]:无论A和B是什么关系,C[A]和C[B]没有从属关系。


def f1(x: Bird): Animal // instance of Function1[Bird, Animal]
def f2(x: Animal): Bird // instance of Function1[Animal, Bird]







* 本文在CC BY-SA(署名-相同方式共享)协议下发布。
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