language-agnostic - null 的目的是什么？

Question

我在编译器类(class)中，我们的任务是从头开始创建我们自己的语言。目前我们的困境是是否包含“null”类型。 null 提供什么目的？我们团队中的一些人认为这并不是绝对必要的，而另一些人则支持 null，只是因为它可以提供额外的灵 active 。

您有什么想法，特别是支持或反对 null 吗？您是否曾经创建过需要 null 的功能？

Answer 1

Null: The Billion Dollar Mistake 。托尼·霍尔:

I call it my billion-dollar mistake. It was the invention of the null reference in 1965. At that time, I was designing the first comprehensive type system for references in an object oriented language (ALGOL W). My goal was to ensure that all use of references should be absolutely safe, with checking performed automatically by the compiler. But I couldn't resist the temptation to put in a null reference, simply because it was so easy to implement. This has led to innumerable errors, vulnerabilities, and system crashes, which have probably caused a billion dollars of pain and damage in the last forty years. In recent years, a number of program analysers like PREfix and PREfast in Microsoft have been used to check references, and give warnings if there is a risk they may be non-null. More recent programming languages like Spec# have introduced declarations for non-null references. This is the solution, which I rejected in 1965.