Generics

Rust generics are monomorphized and usually constrained with traits. TypeScript's generic syntax transfers conceptually, but Rust wants bounds where behavior is used. Planned exercises: 1. choose generic function syntax. 2. recognise Vec<T>. 3. choose a trait bound for formatting or comparison. 4. fill <T>. 5. fill T: Clone. 6. write a generic identity function. 7. write a generic container struct. 8. translate a TS generic helper. 9. fix a generic function by adding the smallest required bound.