I think the names
SIMD4 are strictly worse than the names
Vector4, and I’m actually quite surprised that the core team would recommend this.
Instead of using the common mathematical term, it uses a niche computing term that describes semantics/implementation. Anybody with at least high school knowledge of math knows what a vector is. Much fewer people know what SIMD is.
I have yet to see a compelling argument for why the standard vector types in Swift should not have SIMD semantics. It seems to me that if you want to do vector arithmetic (most commonly in 2, 3 or 4 dimensions) these are the types you should use. And even if there are use cases where someone doesn’t want their vectors or matrices to be SIMD, should that really penalize the common case? That seems unprecedented in Swift naming, and definitely not in line with progressive disclosure.
I think this naming will have a very real effect: these types will be used less. People will not reach for them even when they should, because the names look daunting and strange.