So stateful async would be writing IO. You've passed in a buffer, the length to copy from the buffer. In the continuation, you'd need to know which original cal

So stateful async would be writing IO. You've passed in a buffer, the length to copy from the buffer. In the continuation, you'd need to know which original call you were working with so that you can correlate it with those parameters you passed through. var state = socket.read(buffer); while (!state.poll()) {} state.bytesRead... Stateless async is accepting a connection. In 95% of servers, you just care that a connection was accepted; you don't have any state that persists across the continuation: while (!listeningSocket.poll()) {} var socket = listeningSocket.accept(); Stateless async skirts around many of the issues that Rust async can have (because Pin etc. has to happen because of state).