結論 type Head<T> = T extends [infer U, ...infer _] ? U : never type Tail<T> = T extends [infer _, ...infer U] ? U : never type NecessaryAndSufficientLoop<Union, Arr extends any[]> = Arr extends [] ? [Union] extends [never] ? [] : never : [ Head<Arr> extends Union ? Head<Arr> : ne</arr></arr></union,></t></t>…