Re: [Haskell-cafe] Help with async library and killing child processes

I use my nonblocking library: eg for IRC bot:    let myCallbacks = defaultCallbacks {                                 done_connected = binded,                                 done_reading = response_get tm ref stdgen gsref,                                 done_writing = response_written,                                 done_closed = \pl s -> do                                     putStrLn "peer closed, reconnecting"                                     s <- socket myCallbacks                                     connect pl s "83.140.172.212:6667"                                     return 1,                                 handle_error = \pl s buf len-> do                                     str <- peekCStringLen (buf,fromIntegral len)                                     putStrLn $ "error "++str++", reconnecting"                                     s <- socket myCallbacks                                     connect pl s "83.140.172.212:6667"                                     return 1,                                 tick = binded_tick tm                               }     s <- socket myCallbacks     pl <- epoll 1000     connect pl s "83.140.172.212:6667"     run_loop pl (-1) On 3/19/20 3:40 PM, Michael Hull wrote:

Hi Niklas and Patrick,

Thankyou both for the comments -- this is what I am looking for.

I have a follow-on question, if I have code like

getPages :: IO() getPages = do (page1, page2, page3)      <- runConcurrently $ (,,)      <$> Concurrently (getURL "url1")      <*> Concurrently (getURL "url2")      <*> Concurrently (getURL "url3")

main :: IO() main = do     f <- async getPages     cancel f

Am I guaranteed the the getURL() calls will definitely have either finished, or cancel? (I looked through the source (https://hackage.haskell.org/package/async-2.2.2/docs/src/Control.Concurrent....), and I think so, because runConcurrently is implemented in terms of race, which is implemented using withAsync, but I'm not confident with interpreting Haskell!)

Many thanks,

Mike

On Wed, 18 Mar 2020 at 03:15, Niklas Hambüchen mailto:mail@nh2.me> wrote:

I've you're new to async, also check out my recent rework of the docs that talk about this topic specifically:

https://github.com/simonmar/async/pull/105/files

(To be available in the next release of async.)

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