タプル（固定長の配列）からユニオン型を作り出す

code:memo.ts

type Suit1 = typeof suits1number;

// ^? "spade" | "heart" | "diamond" | "club"

const suits2 = "spade", "heart" as const;

type Suit2 = typeof suits2number;

// ^? "spade" | "heart"

code:memo.ts

type TupleToUnion<T extends unknown[]> = Tnumber;

const a: TupleToUnion<Arr>; // expected to be '1' | '2' | '3'