mutually-exclusive.types.ts

export type MutuallyExclusive<T> = T &
  (
    | {
        [K in keyof T]: K extends `only${string}`
          ? { [_ in K]: true } & {
              [_ in Extract<Exclude<keyof T, K>, `only${string}`>]?: never;
            }
          : never;
      }[keyof T]
    | { [K in Extract<keyof T, `only${string}`>]?: false }
  );