That's what I was trying to get at by talking about making ZII opt-in. If you're using a big chunk of memory — say a matrix, or an array of matrices — it's a win if you can zero-initialize it cheaply or for free, sure. In JS, for example, you'd allocate an ArrayBuffer and use it immediately (via a TypedArray or DataView).

But still, in other parts of the program, ZII is bad! That local or global variable pointing at an ArrayBuffer should definitely not be zero-initialized. Who wants a null pointer, or a pointer to random memory of unknown size? Much better to ensure that a) you actually construct a new TypedArray, and b) you don't use it until it's constructed.

I guess if you see the vast majority of your action happening inside big arrays of structs, pervasive ZII might make sense. But I see most of the action happening in local and temporary variables, where ZII is bad and explicit initialization is what you want.

Moving from JavaScript to TypeScript, to some extent you can get the best of both worlds. TS will do a very good (though not perfect) job of forcing you to initialize everything correctly, but you can still use TypedArray and DataView and take advantage of zero-initialization when you want to.

ZII for local variables reminds me of the SmallTalk / Obj-C thing where you could send messages to nil and they're silently ignored. I don't really know SmallTalk, but in Obj-C, to the best of my knowledge most serious programmers think messages to nil are a bad idea and a source of bugs.

Maybe this is another aspect where the games programming mindset is skewing things (besides the emphasis on low-level performance). In games, avoiding crashes is super important and you're probably willing to compromise on correctness in some cases. In most non-games applications, correctness is super important, and crashing early if something goes wrong is actually preferable.