Convert WHATWG web streams to async iterables and back

whatwg-stream-to-async-iterable.ts

export async function* streamToAsyncIterable<T>(stream: ReadableStream<T>): AsyncIterableIterator<T> {
  const reader = stream.getReader();
  try {
    while (true) {
      const { done, value } = await reader.read();
      if (done) return;
      yield value;
    }
  } finally { reader.releaseLock() }
}

export function asyncIterableToStream<T>(asyncIterable: AsyncIterable<T>): ReadableStream<T> {
  const { readable, writable } = new TransformStream<T, T>();
  (async () => {
    const writer = writable.getWriter();
    try {
      for await (const x of asyncIterable) writer.write(x);
    } finally { writer.close() }
  })();
  return readable;
}