TypeScript: how to declare array of fixed size for type checking at Compile Time

Question

Update: These checks are meant for compile time, not at runtime. In my example, the failed cases are all caught at compile

Answer 1

From Typescript: Can I define an n-length tuple type?, programmatically, with dynamic length:

type Tuple = [TItem, ...TItem[]] & { length: TLength };

type Tuple9 = Tuple;