Structs & Enums

Product types versus sum types, and why enums plus exhaustive `match` eliminate a whole class of bugs that other languages catch at runtime, or don't catch at all.

Named, tuple, and unit structs; construction and update syntax.

`impl` blocks, `self` receivers, and constructors.

Data-carrying variants and modeling state precisely.

Exhaustive matching, guards, and bindings.

Ergonomic partial matching.

The two enums that shape all Rust code.

Structs, tuples, nested patterns, and `@` bindings.

`#[derive(Debug, Clone, PartialEq, ...)]` and when to.

Modeling data so illegal states are unrepresentable.