4 ms·

I mean, why couldn't it? let newvec = vec![fut1, fut2, fut3].map(Future::await).collect() would be equivalent to let f1 = fut1.await(); let f2 =

I mean, why couldn't it? let newvec = vec![fut1, fut2, fut3].map(Future::await).collect() would be equivalent to let f1 = fut1.await(); let f2 = fut2.await(); let f3 = fut3.await(); let newvec = vec![f1,f2,f3]; or vec![fut1,fut2,fut3].map(|fut| fut.await).collect()

Thiez 7y ago
I think you fundamentally misunderstand async await. `vec[fut1, fut2, fut3].map(|fut| fut.await).collect()` will not do what you might expect, although I haven't bothered to read the RFC whether it will be allowed at all. Await must have compiler support and cannot just be some function you call.
- eximius 7y ago
  I am certainly being sloppy, though I think fundamentally misunderstanding it is a bit of an exaggeration. I know you can't await in a non-async function so, at the very least, you'd need (IDR the syntax for async closures?) vec![fut1, fut2, fut3].map_async(async|fut| fut.await).collect() I believe that could be built. Though, now I'm getting myself tripped up. Because I claimed that this is similar to vec![fut1, fut2, fut3].map(Future::await).collect() But I notice that I expect `await` to be a blocking, non-async function. Which, feels strange in that the lambda in the first block needs to be async but the function itself doesn't. > Await must have compiler support and cannot just be some function you call. I'm not saying it doesn't need compiler support. I explicitly state that it does - I just want the magic to be a little more explicit. Moreover, I believe that most programmers think of functions as 'encapsulated code', something that does a thing. In this sense, it matches what await does better than syntax that looks like it's accessing a field. Admittedly, in the purest sense of encapsulation, this method 'escapes' that encapsulation, but I don't consider that terribly important.

Thiez 7y ago

I think you fundamentally misunderstand async await. `vec[fut1, fut2, fut3].map(|fut| fut.await).collect()` will not do what you might expect, although I haven't bothered to read the RFC whether it will be allowed at all. Await must have compiler support and cannot just be some function you call.

eximius 7y ago
I am certainly being sloppy, though I think fundamentally misunderstanding it is a bit of an exaggeration. I know you can't await in a non-async function so, at the very least, you'd need (IDR the syntax for async closures?) vec![fut1, fut2, fut3].map_async(async|fut| fut.await).collect() I believe that could be built. Though, now I'm getting myself tripped up. Because I claimed that this is similar to vec![fut1, fut2, fut3].map(Future::await).collect() But I notice that I expect `await` to be a blocking, non-async function. Which, feels strange in that the lambda in the first block needs to be async but the function itself doesn't. > Await must have compiler support and cannot just be some function you call. I'm not saying it doesn't need compiler support. I explicitly state that it does - I just want the magic to be a little more explicit. Moreover, I believe that most programmers think of functions as 'encapsulated code', something that does a thing. In this sense, it matches what await does better than syntax that looks like it's accessing a field. Admittedly, in the purest sense of encapsulation, this method 'escapes' that encapsulation, but I don't consider that terribly important.