Function watch

packages/platform/deno/src/DenoFileSystem.ts:427–440

(
  backend: Option.Option<FileSystem.WatchBackend["Service"]>,
  path: string,
  options?: FileSystem.WatchOptions
)

  )

const watch = (
  backend: Option.Option<FileSystem.WatchBackend["Service"]>,
  path: string,
  options?: FileSystem.WatchOptions
) =>
  stat(path).pipe(
    Effect.map((info) =>
      backend.pipe(
        Option.flatMap((backend) => backend.register(path, info, options)),
        Option.getOrElse(() => watchNative(path, options))
      )
    ),
    Stream.unwrap
  )

const writeFile: FileSystem.FileSystem["writeFile"] = (path, data, options) => {
  const flag = options?.flag ?? "w"