variances.check

来自「JAVA 语言的函数式编程扩展」· CHECK 代码 · 共 11 行

variances.scala:4: error: covariant type A occurs in contravariant position in type test.Vector[A] of value x
  def append(x: Vector[A]): Vector[A] 
             ^
variances.scala:14: error: covariant type A occurs in contravariant position in type A of value a
    private[this] def setA(a : A) = this.a = a 
                           ^
variances.scala:16: error: covariant type A occurs in invariant position in type test.C[A] with ScalaObject{def this(): object Foo.this.Baz} of object Baz
    object Baz extends C[A]
           ^
three errors found