Map an object type to a union of object paths

object-path.ts

/**
 * Map an object type to a union of object paths
 * @example
 * ```
 * type Foo = { foo: { bar: number, baz: number[] } };
 * type FooPath = ObjectPath<Foo>;
 * //   ^ "foo" | "foo.bar" | "foo.baz"
 * ```
 */
export type ObjectPath<T> = {
  [K in keyof T]:
  K extends string
  ? (
    T[K] extends object
    ? (
      T[K] extends Array<infer U>
      ? K // | `${K}.${number}`
      : K | `${K}.${ObjectPath<T[K]>}`
    )
    : K
  )
  : never;
}[keyof T];