Ohhh. Ok. I see the confusion. That's bad syntax then. The 'a' parameter is not the type of the elements. 'A' is the type of the elements. 'a' is just the "quantity of the type of the type of the elements". Yes, that's a mouthful, and somewhat abstract. This is similar to Agda's universe polymorphism. The reason it exists is because there are two "types of types" (i.e., kinds). Copiable types, and non-copiable types. So, this argument allows you to parametrize a function on both of these kinds. That way, you don't need to write List.length twice: one for copiable types, and once for non-copiable types. Think of Rust generics. 'a' is playing the same role as a "Copiable" trait would in Rust. It is just an extra compile-time argument to avoid boilerplate. But yes, I see how this can be confusing and I think I know how to improve that syntax.

Yes, `Array<U32> & U32` is just `(Array<U32>, U32)` and now that you point it I believe I made a bad choice, no excuses. Also, `arr[3]` doesn't return a number. It returns a copy of the same array, plus a number. So, if the element at index 3 is 123, tthen, `arr[3]` will return `(arr, 123)`. Now, you might be thinking: that's terrible. And yes, it is. I realize it now. I should have made the `arr[3]` syntax return 123. It is there for a very good reason though. It preserves linearity. It is part of the termination argument that makes Bend consistent. But yes, exposing it to the end user was most likely a mistake. I will redesign that syntax. Sorry about it.