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Today's Topics:
1. how does hgearman-worker work? ([email protected])
2. Re: how does hgearman-worker work? (David McBride)
3. Re: how does hgearman-worker work? ([email protected])
4. State monad to help pass around game settings (Dave Martin)
----------------------------------------------------------------------
Message: 1
Date: Thu, 6 Apr 2017 17:37:22 +0200 (CEST)
From: [email protected]
To: [email protected]
Subject: [Haskell-beginners] how does hgearman-worker work?
Message-ID: <[email protected]>
Content-Type: text/plain; charset=UTF-8
A while ago I asked similar question about hgearman client. With help I got in
the List (https://mail.haskell.org/pipermail/beginners/2017-March/017435.html)
and I implemented a gearman client in Haskell. (here the implementation
http://stackoverflow.com/questions/42774191/how-does-hgearman-client-work)
Unfortunately I need again some help be implementation of gearman worker.
I post here only the snippet with the badly implemented code in hope to find
again some help. (Complete implementation:
http://stackoverflow.com/questions/43155857/how-does-hgearman-worker-work)
Right gc -> do
(res, _) <- flip S.runStateT gc $ do
g <- (W.registerWorker name func)
t <- W.runWorker gc (return ())
return t >> return ()
return res
This throws exception:
Couldn't match expected type `S.StateT
Network.Gearman.Internal.GearmanClient IO a0'
with actual type `IO GHC.Conc.Sync.ThreadId'
In a stmt of a 'do' block: t <- W.runWorker gc (return ())
In the second argument of `($)', namely
`do { g <- (W.registerWorker name func);
t <- W.runWorker gc (return ());
return t >> return () }
What do I wrong with W.runWorker gc (return ())?
runWorker :: GearmanClient -> Gearman () -> IO ThreadId
https://hackage.haskell.org/package/hgearman-0.1.0.2/docs/Network-Gearman-Worker.html
Best regards,
Alexei
------------------------------
Message: 2
Date: Thu, 6 Apr 2017 13:54:30 -0400
From: David McBride <[email protected]>
To: Maxim 2001 <[email protected]>, The Haskell-Beginners Mailing List
- Discussion of primarily beginner-level topics related to Haskell
<[email protected]>
Subject: Re: [Haskell-beginners] how does hgearman-worker work?
Message-ID:
<can+tr418ckrpodreeqprmpsrul+zsd3oqxfnprbeee_kc3v...@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
There are a couple problems. One is that runWorker has a type of IO
ThreadId. I have no idea why he would write it that way in his API.
If you want to run it from within StateT GearmanClient IO, you must
use liftIO.
liftIO :: (MonadIO m) => IO a -> StateT s IO
instance MonadIO (StateT s IO) where
liftIO :: IO a -> StateT s IO a
liftIO $ runWorker gc whatever.
When you are working in monadic code, you connect monadic components
based on their types. If you are a procedure
someprocedure :: IO ???
Then every statement you used must some form of ???. runWorker
returns (IO ThreadId), return () returns (IO ()), return res returns
IO (whatever type res is). I'm not sure what you intend to do with
the threadId, save it or ignore it, but you might try something like
this.
someprocedure' :: IO (Maybe ThreadId)
someprocedure' = do
connectGearman >>= \case
Left e -> return Nothing
Right gc -> do
(res, _) <- flip runStateT gc $ do
g <- registerWorker undefined undefined
t <- liftIO $ runWorker gc undefined
return $ Just t
return res
This is just a guess based on what I know about gearman and that
particular api choice. He may have intended you to use runWorker
outside of the setup phase. He certainly doesn't prevent it.
someprocedure' :: IO ()
someprocedure' = do
gs <- connectGearman >>= \case
Left e -> return []
Right gc -> do
(res, _) <- flip runStateT gc $ do
g <- registerWorker undefined undefined
g2 <- registerWorker undefined undefined
return $ [g,g2]
return res
mapM_ (\g -> runWorker g (return ())) gs
On Thu, Apr 6, 2017 at 11:37 AM, <[email protected]> wrote:
> A while ago I asked similar question about hgearman client. With help I got
> in the List
> (https://mail.haskell.org/pipermail/beginners/2017-March/017435.html) and I
> implemented a gearman client in Haskell. (here the implementation
> http://stackoverflow.com/questions/42774191/how-does-hgearman-client-work)
>
> Unfortunately I need again some help be implementation of gearman worker.
>
> I post here only the snippet with the badly implemented code in hope to find
> again some help. (Complete implementation:
> http://stackoverflow.com/questions/43155857/how-does-hgearman-worker-work)
>
> Right gc -> do
> (res, _) <- flip S.runStateT gc $ do
> g <- (W.registerWorker name func)
> t <- W.runWorker gc (return ())
> return t >> return ()
>
> return res
>
> This throws exception:
> Couldn't match expected type `S.StateT
> Network.Gearman.Internal.GearmanClient IO a0'
> with actual type `IO GHC.Conc.Sync.ThreadId'
> In a stmt of a 'do' block: t <- W.runWorker gc (return ())
> In the second argument of `($)', namely
> `do { g <- (W.registerWorker name func);
> t <- W.runWorker gc (return ());
> return t >> return () }
>
>
> What do I wrong with W.runWorker gc (return ())?
>
> runWorker :: GearmanClient -> Gearman () -> IO ThreadId
> https://hackage.haskell.org/package/hgearman-0.1.0.2/docs/Network-Gearman-Worker.html
>
> Best regards,
> Alexei
> _______________________________________________
> Beginners mailing list
> [email protected]
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
------------------------------
Message: 3
Date: Thu, 6 Apr 2017 23:43:19 +0200 (CEST)
From: [email protected]
To: David McBride <[email protected]>, The Haskell-Beginners Mailing
List - Discussion of primarily beginner-level topics related to
Haskell <[email protected]>
Subject: Re: [Haskell-beginners] how does hgearman-worker work?
Message-ID: <[email protected]>
Content-Type: text/plain; charset=UTF-8
Thank you very much, David.
> If you want to run it from within StateT GearmanClient IO, you must
> use liftIO.
The execution of the worker implementation below shows the ThreadId but the
worker doesn't grab any job from gearmand as expected. GRAB_JOB, wich sends
gmLoop
(https://github.com/jperson/hgearman-client/blob/master/Network/Gearman/Worker.hs#L29),
appears in gearmand logs but the worker close the connection before gearmand
sends GEARMAN_COMMAND_JOB_ASSIGN replay. It looks like the worker does not
execute gmWait.
{-# LANGUAGE LambdaCase #-}
import qualified Control.Monad.State as S
import qualified Data.ByteString.Char8 as B
import qualified Network.Gearman.Client as C
import qualified Network.Gearman.Worker as W
import Network.Gearman.Internal (Function, Port)
import Network.Socket (HostName)
import GHC.Conc.Sync (ThreadId)
main :: IO ()
main = do
work >>= \ case
Nothing -> putStrLn "nothing"
Just t -> putStrLn $ show t
return ()
work :: IO (Maybe ThreadId)
work = do
connect >>= \case
Left e -> error $ B.unpack e
Right gc -> do
(res, _) <- flip S.runStateT gc $ do
g <- W.registerWorker ((B.pack "foo")::Function) (\_ -> B.pack "bar")
t <- S.liftIO $ W.runWorker gc (return g)
return $ Just t
return res
where
connect = C.connectGearman (B.pack "worker-id-123") ("localhost"::HostName)
(4730::Port)
> This is just a guess based on what I know about gearman and that
> particular api choice. He may have intended you to use runWorker
> outside of the setup phase. He certainly doesn't prevent it.
>
> someprocedure' :: IO ()
> someprocedure' = do
> gs <- connectGearman >>= \case
> Left e -> return []
> Right gc -> do
> (res, _) <- flip runStateT gc $ do
> g <- registerWorker undefined undefined
> g2 <- registerWorker undefined undefined
> return $ [g,g2]
> return res
>
> mapM_ (\g -> runWorker g (return ())) gs
>
I'm not sure it could work in this way because runWorker :: GearmanClient ->
Gearman () -> IO ThreadId and connectGearman result is of type IO (Either
GearmanError GearmanClient)
Best regards,
Alexei
> On 06 April 2017 at 19:54 David McBride <[email protected]> wrote:
>
>
> There are a couple problems. One is that runWorker has a type of IO
> ThreadId. I have no idea why he would write it that way in his API.
> If you want to run it from within StateT GearmanClient IO, you must
> use liftIO.
>
> liftIO :: (MonadIO m) => IO a -> StateT s IO
>
> instance MonadIO (StateT s IO) where
> liftIO :: IO a -> StateT s IO a
>
> liftIO $ runWorker gc whatever.
>
> When you are working in monadic code, you connect monadic components
> based on their types. If you are a procedure
>
> someprocedure :: IO ???
>
> Then every statement you used must some form of ???. runWorker
> returns (IO ThreadId), return () returns (IO ()), return res returns
> IO (whatever type res is). I'm not sure what you intend to do with
> the threadId, save it or ignore it, but you might try something like
> this.
>
> someprocedure' :: IO (Maybe ThreadId)
> someprocedure' = do
> connectGearman >>= \case
> Left e -> return Nothing
> Right gc -> do
> (res, _) <- flip runStateT gc $ do
> g <- registerWorker undefined undefined
> t <- liftIO $ runWorker gc undefined
> return $ Just t
> return res
>
> This is just a guess based on what I know about gearman and that
> particular api choice. He may have intended you to use runWorker
> outside of the setup phase. He certainly doesn't prevent it.
>
> someprocedure' :: IO ()
> someprocedure' = do
> gs <- connectGearman >>= \case
> Left e -> return []
> Right gc -> do
> (res, _) <- flip runStateT gc $ do
> g <- registerWorker undefined undefined
> g2 <- registerWorker undefined undefined
> return $ [g,g2]
> return res
>
> mapM_ (\g -> runWorker g (return ())) gs
>
>
>
> On Thu, Apr 6, 2017 at 11:37 AM, <[email protected]> wrote:
> > A while ago I asked similar question about hgearman client. With help I got
> > in the List
> > (https://mail.haskell.org/pipermail/beginners/2017-March/017435.html) and I
> > implemented a gearman client in Haskell. (here the implementation
> > http://stackoverflow.com/questions/42774191/how-does-hgearman-client-work)
> >
> > Unfortunately I need again some help be implementation of gearman worker.
> >
> > I post here only the snippet with the badly implemented code in hope to
> > find again some help. (Complete implementation:
> > http://stackoverflow.com/questions/43155857/how-does-hgearman-worker-work)
> >
> > Right gc -> do
> > (res, _) <- flip S.runStateT gc $ do
> > g <- (W.registerWorker name func)
> > t <- W.runWorker gc (return ())
> > return t >> return ()
> >
> > return res
> >
> > This throws exception:
> > Couldn't match expected type `S.StateT
> > Network.Gearman.Internal.GearmanClient IO
> > a0'
> > with actual type `IO GHC.Conc.Sync.ThreadId'
> > In a stmt of a 'do' block: t <- W.runWorker gc (return ())
> > In the second argument of `($)', namely
> > `do { g <- (W.registerWorker name func);
> > t <- W.runWorker gc (return ());
> > return t >> return () }
> >
> >
> > What do I wrong with W.runWorker gc (return ())?
> >
> > runWorker :: GearmanClient -> Gearman () -> IO ThreadId
> > https://hackage.haskell.org/package/hgearman-0.1.0.2/docs/Network-Gearman-Worker.html
> >
> > Best regards,
> > Alexei
> > _______________________________________________
> > Beginners mailing list
> > [email protected]
> > http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
------------------------------
Message: 4
Date: Thu, 6 Apr 2017 21:26:09 -0400
From: Dave Martin <[email protected]>
To: [email protected]
Subject: [Haskell-beginners] State monad to help pass around game
settings
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"
I'm trying to write a game with a "settings menu" where the user can adjust
gameplay options. Right now I pass all the settings around as parameters. I'm
trying to figure out how to use the State monad to simplify this task, but I
can't figure out how to start. Or maybe my whole design approach is
wrongheaded, and not in keeping with best practices. Haskell is my first
language. This is the kind of thing I have now:
mainM color shape =
putStrLn "\n\nMain Menu" >>
(putStrLn . unlines) [
"(1) Set",
"(2) Display",
"(3) Quit"] >>
putStr "? " >>
getChar >>= \c ->
case c of
'1' -> set color shape
'2' -> display color shape
'3' -> return ()
_ -> mainM color shape
set color shape =
putStrLn "\n\nSettings" >>
(putStrLn . unlines) [
"(1) Color",
"(2) Shape",
"(3) Main Menu"] >>
putStr "? " >>
getChar >>= \c ->
case c of
'1' -> setColor color shape
'2' -> setShape color shape
'3' -> mainM color shape
_ -> set color shape
setColor color shape =
putStr ("\n\nColor is " ++ color ++ ". New color? ") >>
getLine >>= \cs ->
set cs shape
setShape color shape =
putStr ("\n\nShape is " ++ shape ++ ". New shape? ") >>
getLine >>= \cs ->
set color cs
display color shape =
putStrLn ("\n\nColor is " ++ color ++ ". Shape is " ++ shape ++ ".") >>
mainM color shape
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