Within the type system of a programming language, covariance and contravariance refers to the ordering of types from narrower to wider and their interchangeability or equivalence in certain situations (such as parameters, generics, and return types)
Please show a good example for covariance and contravariance in Java.
java covariance contravarianceI didn't attend PDC 2008, but I heard some news that C# 4.0 is announced to support Generic covariance and contra-variance. That …
c# c#-4.0 covariance contravariance generic-varianceI am just trying to understand the extends keyword in Java Generics. List<? extends Animal> means we can …
java generics covariance extends contravarianceToday, I read some articles about Covariance, Contravariance (and Invariance) in Java. I read the English and German Wikipedia article, …
java covariance contravarianceFollowing on from this question, can someone explain the following in Scala: class Slot[+T] (var some: T) { // DOES NOT …
generics scala covariance contravarianceI am having trouble understanding the difference between covariance and contravariance.
c# c#-4.0 covariance contravarianceI've come across these in a textbook I am reading on C#, but I am having difficulty understanding them, probably …
c# .net interface covariance contravarianceFirst of, I have read many explanations on SO and blogs about covariance and contravariance and a big thanks goes …
c# c#-4.0 covariance contravarianceRecently I found a very surprising behavior in c#. I had a method which takes IEnumerable<Object> as …
c# covariance contravarianceIn Java I might do this: class MyClass { private List<? extends MyInterface> list; public void setList(List<…
java generics scala covariance contravariance