I understood what you meant. I just disagree about priorities. Conceptually, every array access (absent dependent types) can produce a null value because the in

I understood what you meant. I just disagree about priorities. Conceptually, every array access (absent dependent types) can produce a null value because the index might be out of bounds. Languages that eliminate null values in other areas typically fail to deal with the array indexing issue at the type level, which seems at least as prevalent in real-world code as null pointer deferences, if not more so. Regarding the category error, on many platforms, Rust panics use the same underlying implementation mechanism as C++ exceptions. In general, Rust library code is expected to be panic-safe. Some well-known Rust tools use panics for control flow (in the same way one would abuse exceptions). The standard test framework depends on recoverable panics, if I recall correctly. The Rust language gives exceptions a different name and does not provide convenient syntax for handling them, but it still has to deal with the baggage associated with them, and so do Rust library authors who do not want to place restrictions on how their code is reused. It's not necessarily a bad approach, to be clear: avoiding out-of-bounds indexing errors completely is hard.