Those Option and Result panic message improvements will be super helpful to people getting started with Rust — at least I know they would have been when I was starting out.
I’ve been writing rust for years, having line numbers for where they’re invoked will be super helpful to me. It might be the most exciting feature to come to rust IMO. Simply not needing to find the one line in the middle of the 50 line backtrace that is actually my code just for an unwrap panic is going to save me immense amounts of debugging time.
I have a feeling that writing parsers, be it for text or binary formats, will be so much easier with the new slice patterns. Also emulators and VMs will be much simpler to implement.
Looking forward to trying out that new matches! macro.