I asked GPT-5 about it before writing the above comment and got a pretty interesting answer about how, for example, you can’t write a function that takes a number as an argument and returns an array of that length (length enforced by the type system). You can partly get there with tuple types but you have to enumerate every length explicitly. And it only works if you pass a number literal to the function. If you pass a variable of type number, it can’t infer the particular number it is.