References only have a single bit available as a niche (the null byte), which Option makes use of for null pointer optimization (https://doc.rust-lang.org/std/option/index.html#representati...).

In principle, you Rust could create something like std::num::NonZero and its corresponding sealed trait ZeroablePrimitive to mark that two bits are unused. But that doesn't exist yet as far as I know.

Asciidoc corresponds directly to DocBook XML. They're two formats with exactly the same semantics.

MCP is an example of "worse is better". Everyone knows that it's not very good, but it gets the job done.

It's been a while since I've played in the area, but is PCA still the go to method for dimensionality reduction?

This reminds me of when I provided some impressions of Erlang as a newcomer to their mailing list.

One of my suggestions was that they include hash tables, rather than rely on records (linked lists with named key). Got flamed as ignorant, and I've never emailed that mailing list again. A while later, they ended up adding hash tables to the language.