type Target = [number, string, boolean] & { att: string; };

type A = Readonly<Target>; // wishful thinking

type Head1 = Target extends [infer H, ...infer Tail] ? H : never; // doesn't work
type Head2 = Target extends [infer H, ...any[]] ? H : never; // works

type Tail1 = Target extends [infer H, ...infer Tail] ? Tail : never; // doesn't work
type Tail2 = Target extends [any, ...infer Tail] ? Tail : never; // doesn't work

type ReverseHead1 = Target extends [...infer RTail, infer RH] ? RH : never; // doesn't work
type ReverseHead2 = Target extends [...any[], infer RH] ? RH : never; // doesn't work

type ReverseTail1 = Target extends [...infer RTail, infer RH] ? RTail : never; // doesn't work
type ReverseTail2 = Target extends [...infer RTail, any] ? RTail : never; // doesn't work