https://skyzh.github.io/type-exercise-in-rust https://skyzh.github.io/type-exercise-in-rust/chapter-1-type-family https://skyzh.github.io/type-exercise-in-rust/chapter-2-type-catalog https://skyzh.github.io/type-exercise-in-rust/preface https://skyzh.github.io/type-exercise-in-rust/setup