Null Is Not the Billion Dollar Mistake. A Counter-Rant (2015)

Well, this is a load of hogwash.<p>Null is definitely the billion dollar mistake. It’s not the “null” value however, since this could indeed be seen as a badly implemented option monad.<p>It’s the implicit nullability of all reference types which is the mistake, since it leads to undefined behaviour at runtime.<p>Also; in regards to the linked style discussion in the post; you’re wrong about all of it :p

The biggest problem is always just going to be that it breaks any understanding or concept of a type system. When object.doThing().doOtherThing() can fail because the result of doThing() can be null, you suddenly have to fill your entire code base with unreadable cruft to avoid that happening. Because it&#x27;s not just that one method where this is possible.<p>It especially doesn&#x27;t help in languages like Java, where nulls completely subvert static types and static type checking and it turns a whole class of issues into runtime errors.<p>Allowing null means you&#x27;re implicitly codifying Type class | null for every single reference type everywhere in your code. By doing it implicitly, you&#x27;re not providing any semantics in the programming language or in the runtime to be able to deal with it at the same abstraction level as the code around any particular point where something can be null. This is incredibly error prone and makes for ugly, brittle code.<p>Yeah, it&#x27;s a billion dollar mistake.

&gt; JavaScript itself is a beacon of usefulness that is inversely proportional to its purity or beauty, so long story short: ...<p>How can I take this seriously. The language&#x27;s shortcomings is from being written practically overnight, not from inverse proportional value elsewhere. This post might be a $100 mistake.

Where UserName Is Not Null<p>Filters out the records where UserName is not Null.<p>Where UserName Is Null<p>Filters out the records where UserName is null and possibly didn&#x27;t finish the registration process.

Coincidentally surely, and not Dunning-Kreugur, that this exact thing proved to be another literal 2 comma line item just last week.

Stopped reading at &quot;Functional programming languages like to make use of the Optional “monad” ... but that’s just another way of modelling NULL.&quot; It is clear he doesn&#x27;t understand simple things like Option and the purpose of that and monads.