Seems like we have to live with `async`, let's think if we can improve how it's
used. I [used Nim async](https://github.com/al6x/nim/tree/main/nodem) and it
looks to me, compared to the experience of Async in JavaScript, there are
couple of things could be improved.
1 Use same `await` instead of `wait_for` if async needs to be called in sync
function.
2 No sync IO instead of async proc allowed, mark all non-async IO with `syncio`
and throw error if it's used in async proc. It is ok to block async event loop
with CPU, it terrible if it's blocked with sync-IO.
3 Allow implicit return from async functions.
4 Allow to return future from async function.
5 Rename `async_check` as `spawn(Future)` or `check(Future)`.
6 Remove `run_forewer`, if there's at least one listener registered on the
event loop keep process running.
7 Don't print ugly multi-page async error stack traces, if it can't be made
short and clean it's better to not print it at all, as they are usually useless
anyway.
8 `with_timeout` should throw error or return `Future[T]`, not `Future[bool]`.
9 Maybe Stop using `{.async.}` the code is noisy, if function returns `Future`
it's async.
What do you think? If we have to live with it, let's make it great! :)
# Examples
None of it works right now:
a)
proc a: Future[int] = 10
Run
b)
proc a: Future[int] {.async.} = 10
Run
c)
proc a: Future[int] {.async.} = return 10
proc b: Future[int] {.async.} = a()
Run
d)
proc somefn1: Future[int] {.async.} = return 10
proc somefn2: Future[int] {.async.} = return somefn1()
Run
e) How the async error message looks like
nim c -r nodem/greeting_example/user.nim
/alex/projects/nim/nodem/greeting_example/user.nim(14) user
/alex/projects/nim/nodem/nodem.nim(359) run
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1935) waitFor
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1627) poll
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1368) runOnce
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(208)
processPendingCallbacks
/balex/applications/nim-1.4.2/lib/pure/asyncmacro.nim(29)
callNimAsyncContinue
/alex/projects/nim/nodem/nodem/netm.nim(120) callIter
[[reraised from:
/alex/projects/nim/nodem/greeting_example/user.nim(14) user
/alex/projects/nim/nodem/nodem.nim(359) run
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1935) waitFor
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1627) poll
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1368) runOnce
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(208)
processPendingCallbacks
/balex/applications/nim-1.4.2/lib/pure/asyncmacro.nim(29)
call_nimported_functionNimAsyncContinue
/balex/applications/nim-1.4.2/lib/pure/asyncmacro.nim(145)
call_nimported_functionIter
/balex/applications/nim-1.4.2/lib/pure/asyncfutures.nim(372) read
]]
[[reraised from:
/alex/projects/nim/nodem/greeting_example/user.nim(14) user
/alex/projects/nim/nodem/nodem.nim(359) run
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1935) waitFor
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1627) poll
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1368) runOnce
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(208)
processPendingCallbacks
/balex/applications/nim-1.4.2/lib/pure/asyncmacro.nim(29)
call_nimported_functionNimAsyncContinue
/balex/applications/nim-1.4.2/lib/pure/asyncmacro.nim(145)
call_nimported_functionIter
/balex/applications/nim-1.4.2/lib/pure/asyncfutures.nim(372) read
]]
[[reraised from:
/alex/projects/nim/nodem/greeting_example/user.nim(14) user
/alex/projects/nim/nodem/nodem.nim(359) run
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1935) waitFor
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1627) poll
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1368) runOnce
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(208)
processPendingCallbacks
/balex/applications/nim-1.4.2/lib/pure/asyncmacro.nim(29)
say_hiNimAsyncContinue
/balex/applications/nim-1.4.2/lib/pure/asyncmacro.nim(145) say_hiIter
/balex/applications/nim-1.4.2/lib/pure/asyncfutures.nim(372) read
]]
[[reraised from:
/alex/projects/nim/nodem/greeting_example/user.nim(14) user
/alex/projects/nim/nodem/nodem.nim(359) run
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1935) waitFor
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1627) poll
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1368) runOnce
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(208)
processPendingCallbacks
/balex/applications/nim-1.4.2/lib/pure/asyncmacro.nim(29)
selfNimAsyncContinue
/balex/applications/nim-1.4.2/lib/pure/asyncmacro.nim(145) selfIter
/balex/applications/nim-1.4.2/lib/pure/asyncfutures.nim(372) read
]]
[[reraised from:
/alex/projects/nim/nodem/greeting_example/user.nim(14) user
/alex/projects/nim/nodem/nodem.nim(359) run
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1935) waitFor
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1627) poll
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1368) runOnce
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(208)
processPendingCallbacks
/balex/applications/nim-1.4.2/lib/pure/asyncfutures.nim(420)
asyncCheckCallback
]]
Error: unhandled exception: Timed out, connection closed
Async traceback:
/alex/projects/nim/nodem/greeting_example/user.nim(14) user
/alex/projects/nim/nodem/nodem.nim(359) run
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1935) waitFor
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1627) poll
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1368) runOnce
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(208)
processPendingCallbacks
/balex/applications/nim-1.4.2/lib/pure/asyncmacro.nim(29)
callNimAsyncContinue
/alex/projects/nim/nodem/nodem/netm.nim(120) callIter
#[
/alex/projects/nim/nodem/greeting_example/user.nim(14) user
/alex/projects/nim/nodem/nodem.nim(359) run
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1935) waitFor
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1627) poll
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1368) runOnce
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(208)
processPendingCallbacks
/balex/applications/nim-1.4.2/lib/pure/asyncmacro.nim(29)
call_nimported_functionNimAsyncContinue
/balex/applications/nim-1.4.2/lib/pure/asyncmacro.nim(145)
call_nimported_functionIter
/balex/applications/nim-1.4.2/lib/pure/asyncfutures.nim(372) read
]#
#[
/alex/projects/nim/nodem/greeting_example/user.nim(14) user
/alex/projects/nim/nodem/nodem.nim(359) run
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1935) waitFor
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1627) poll
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1368) runOnce
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(208)
processPendingCallbacks
/balex/applications/nim-1.4.2/lib/pure/asyncmacro.nim(29)
call_nimported_functionNimAsyncContinue
/balex/applications/nim-1.4.2/lib/pure/asyncmacro.nim(145)
call_nimported_functionIter
/balex/applications/nim-1.4.2/lib/pure/asyncfutures.nim(372) read
]#
#[
/alex/projects/nim/nodem/greeting_example/user.nim(14) user
/alex/projects/nim/nodem/nodem.nim(359) run
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1935) waitFor
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1627) poll
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1368) runOnce
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(208)
processPendingCallbacks
/balex/applications/nim-1.4.2/lib/pure/asyncmacro.nim(29)
say_hiNimAsyncContinue
/balex/applications/nim-1.4.2/lib/pure/asyncmacro.nim(145)
say_hiIter
/balex/applications/nim-1.4.2/lib/pure/asyncfutures.nim(372) read
]#
#[
/alex/projects/nim/nodem/greeting_example/user.nim(14) user
/alex/projects/nim/nodem/nodem.nim(359) run
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1935) waitFor
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1627) poll
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(1368) runOnce
/balex/applications/nim-1.4.2/lib/pure/asyncdispatch.nim(208)
processPendingCallbacks
/balex/applications/nim-1.4.2/lib/pure/asyncmacro.nim(29)
selfNimAsyncContinue
/balex/applications/nim-1.4.2/lib/pure/asyncmacro.nim(145) selfIter
/balex/applications/nim-1.4.2/lib/pure/asyncfutures.nim(372) read
]#
Exception message: Timed out, connection closed
Exception type: [Exception]
Error: execution of an external program failed:
'/alex/projects/nim/build/user '
Run
P.S.
Eventually though, I hope Nim deprecate async and use better approaches, async
is too low level and designed for machines, not humans, working with async is
like writting C by hands.
