`BitSlice` or a sound way to implement one

This is definitely only possible with language support. At the assembly level you can overwrite individual bits at a memory address with AND/ORD. But at the library level you're faced with the problem that you can't overwrite neighbouring bits you don't own, and you can't read+update them because they may be uninitialized or be being written concurrently. It sucks that seemingly no low-level language lets you manipulate data at bit-level granularity the same way you can at byte-level. (I did look around at some others recently because doing this was so frustrating in rust). Is there actually a hard reason for it? I can only think of bad reasons like: * "Pointers are byte level" - You could use the top three bits for a bit-offset, or use fat pointers for sub-byte-aligned data. * "Reading/writing individual bits requires more instructions" - That'd usually be a small price to pay for better cache utilization, and it's something people would opt-in to by using sub-byte sized types. What's the good case against it, assuming you were making a rust-like language from scratch and weren't worried about additional complexity or backwards-compatibility?