确定并描述Scala的泛型类型约束 [英] Identify and describe Scala's generic type constraints

问题描述

我见过<：和>：和<％等，有人可以给（或定位）这些描述吗？什么是可能的限制，他们做什么，以及什么时候使用它们的例子？

S <：T 意味着 S 是 T 的子类型。这也被称为上限类型。同样， S>：T 表示 S 是超类型 T ，一个较低的类型绑定。

S <％T 是一个视图边界，表示 S 必须配备查看，将其值映射到类型 T 的值中。

这也让我感到困惑，而且我有一位来自伯克利的编程语言大师。

I've seen "<:" and ">:" and "<%" etc, can someone give (or locate) a good description of these? What are the possible constraints, what do they do, and whats an example of when to use them?

解决方案

S <: T means that S is a subtype of T. This is also called an upper type bound. Similarly, S >: T means that S is a supertype of T, a lower type bound.

S <% T is a view bound, and expresses that S must come equipped with a view that maps its values into values of type T.

It's confusing for me too, and I have a Masters in programming languages from Berkeley.

这篇关于确定并描述Scala的泛型类型约束的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！