[eyelidlessness]

I can’t speak to Metal, but you’ve gotten at what I wanted to be contrary about in my sibling comment: number (or equivalent, and same goes for other primitives) is an inadequate type. If it’s an array index, it’s not just any number. If it’s a range restricted count of something like pixels, it’s not just any number! Any code in almost any language can box these types so they’re safe to use, but almost no one ever does except in ML langs (or maybe Javaish ones) because across the board it’s a huge bunch of ceremony for mostly worse performance.