There is some code that wants to be generic over its executor. This is particularly true of something like parsing code, where you logically have a "get more da

There is some code that wants to be generic over its executor. This is particularly true of something like parsing code, where you logically have a "get more data" call and you really don't care about the details of the call otherwise. So if the user provided a synchronous "get more data" source, you'd want the parse method to be synchronous; if it were asynchronous, you'd want it the parse method to be asynchronous. That's basically the genesis of the idea of maybe-async. I've cooled tremendously on the idea, personally, because it turns out that a lot of code has rather different designs throughout the entire stack if you're relying on sync I/O versus async I/O, and this isn't all that useful in practice.