But why is it &str not StringView? The main reason I see is that the lifetimes are more natural as &'a str instead of StringView<'a>.
I don't think this inconsistency is worth it. It is really just a hack that reinterpretes the (vtable, ptr) of an unsized type as (len, ptr). The only other type that does this are slices.
Or maybe the real reason is that Rust can't be generic over lifetimes, so you would need StringView and StringViewMut. But even that it doesn't seem like a huge deal to me for a simpler "language" (my understanding is that these hacks are actually done in std, but it's been a while since I looked at the code).
I don't think this inconsistency is worth it. It is really just a hack that reinterpretes the (vtable, ptr) of an unsized type as (len, ptr). The only other type that does this are slices.
Or maybe the real reason is that Rust can't be generic over lifetimes, so you would need StringView and StringViewMut. But even that it doesn't seem like a huge deal to me for a simpler "language" (my understanding is that these hacks are actually done in std, but it's been a while since I looked at the code).