public class EnumerableProcess{async static public Task<IEnumerable<string>> ReadLineAsync(string path){           List<string> list = new List<string>();using (StreamReader reader = File.OpenText(path)){while (await reader.ReadLineAsync() is string result){list.Add(result);await Task.Delay(100);}}return list;}}

 var r = await EnumerableProcess.ReadLineAsync(path);foreach (var item in r){Console.WriteLine(item);}

public interface IAsyncDisposable
{ValueTask DisposeAsync();
}

public interface IAsyncEnumerator<out T> : IAsyncDisposable
{T Current { get; }ValueTask<bool> MoveNextAsync();
}

public interface IAsyncEnumerable<out T>
{IAsyncEnumerator<T> GetAsyncEnumerator();
}

    sealed class AsyncFileProcess : IAsyncEnumerable<string>, IAsyncEnumerator<string>{private readonly StreamReader _reader;private bool _disposed;public AsyncFileProcess(string path){_reader = File.OpenText(path);_disposed = false;}public string Current { get; private set; }public IAsyncEnumerator<string> GetAsyncEnumerator(){return this;}async public ValueTask<bool> MoveNextAsync(){await Task.Delay(100);            var result = await _reader.ReadLineAsync();Current = result;return result != null;}async public ValueTask DisposeAsync(){await Task.Run(() => Dispose());}private void Dispose(){Dispose(true);GC.SuppressFinalize(this);}private void Dispose(bool disposing){if (!this._disposed){if (_reader != null){_reader.Dispose();}_disposed = true;}}}

var process = new AsyncFileProcess("SourceFile.txt");
try
{await foreach (var s in process){Console.WriteLine(s);}Console.ReadLine();
}
finally
{await process.DisposeAsync();
}