Technical nits: Slices and other DSTs

[QuineDot]

I don't think you ever cover what a non-Sized type, aka dynamically sized type (DST), is.

Here you call &str and &[u8] "scalar types", and... while the reference is, I suppose... the underlying (DST) slice contains multiple values, so I found their inclusion surprising.

Then later on you refer to &[T] as a slice. This is common nomenclature, but I feel it's worth pointing out that a [T] is more properly the slice, it is dynamically sized, and this is why you typically see it behind a reference (or other pointer like in a Box). And then on this page you could say a str is basically a [u8] with invariants (valid UTF8 encoding).

Incidentally, that page says there are two Rust string types, but there are many others, such as Arc<str> or Cow<'_, str>.

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Then later on you say

Recursive data types or data types with dynamic sizes need to use a Box

But that's incorrect:

• There are no dynamic sizes here in Rust terminology; List<T> has a static size
• If you attempt to write List without the Box, it has infinite size -- but still not dynamic
• Slices have dynamic sizes but don't need a Box

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When you get around to trait objects, you can mention that they're DSTs too, and that's why you typically see them in a Box (but may also seem them behind a reference, in an Arc, ...).