If the task that bar() will return is created when you first call it, then you're right, we didn't gain much. However, the task may have already been running for a long time behind the scenes, we may have done things in parallel with that run, and now that we need the result, we can block.
For example:
myHttpClient.StartReq1()
myHttpClient.StartReq2()
auto Res1 = await myHttpClient.WaitReq1()
auto res2 = await myHttpClient.WaitReq2()
Given the lack of generics, you would get a much worse interface. Btw, here is what a non-buffering channel would look like in Java:
class Channel<T> {
T value;
void publish(T value) {
synchronized(this) {
this.value = value;
try {
this.wait();
} catch (InterruptedException e) {}
}
}
T consume() {
synchronized(this) {
this.notify();
return this.value;
}
}
}