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Today's Topics:
1. Re: ODP: howto Pipe (PICCA Frederic-Emmanuel)
2. Re: ODP: howto Pipe (PICCA Frederic-Emmanuel)
3. Re: ODP: howto Pipe (Marcin Mrotek)
----------------------------------------------------------------------
Message: 1
Date: Sat, 20 Feb 2016 10:12:26 +0000
From: PICCA Frederic-Emmanuel
<[email protected]>
To: "The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell" <[email protected]>
Subject: Re: [Haskell-beginners] ODP: howto Pipe
Message-ID:
<a2a20ec3b8560d408356cac2fc148e53b303b...@sun-dag3.synchrotron-soleil.fr>
Content-Type: text/plain; charset="us-ascii"
Hello
first a big thanks your for all your comment :)
I end-up with this solution
data Diffractometer = Diffractometer { difEngineList :: (ForeignPtr
HklEngineList)
, difGeometry :: (ForeignPtr HklGeometry)
, difDetector :: (ForeignPtr HklDetector)
, difSample :: (ForeignPtr HklSample)
}
deriving (Show)
newDiffractometer :: Factory -> Geometry -> Detector -> Sample -> IO
Diffractometer
newDiffractometer f g d s = do
f_engines <- newEngineList f
f_geometry <- newGeometry f g
f_detector <- newDetector d
f_sample <- newSample s
withForeignPtr f_sample $ \sample ->
withForeignPtr f_detector $ \detector ->
withForeignPtr f_geometry $ \geometry ->
withForeignPtr f_engines $ \engines -> do
c_hkl_engine_list_init engines geometry detector sample
return $ Diffractometer f_engines f_geometry f_detector
f_sample
solve' :: Ptr HklEngine -> CSize -> Engine -> IO (ForeignPtr HklGeometryList)
solve' engine n (Engine _ ps _) = do
let positions = [v | (Parameter _ v _) <- ps]
withArray positions $ \values ->
c_hkl_engine_pseudo_axis_values_set engine values n unit nullPtr
>>= newForeignPtr c_hkl_geometry_list_free
solveTrajPipe' :: Diffractometer -> Pipe Engine Geometry IO ()
solveTrajPipe' dif = forever $ do
-- Inside here we are using `StateT Int (Consumer a IO) r`
e <- await
let name = engineName e
solutions <- lift $ withForeignPtr (difEngineList dif) $ \engines ->
withCString name $ \cname -> do
engine <- c_hkl_engine_list_engine_get_by_name engines cname nullPtr
n <- c_hkl_engine_pseudo_axis_names_get engine >>= darrayStringLen
solutions <- solve' engine n e >>= getSolution0
return solutions
yield solutions
solveTrajPipe :: Factory -> Geometry -> Detector -> Sample -> Pipe Engine
Geometry IO ()
solveTrajPipe f g d s = do
dif <- lift $ newDiffractometer f g d s
solveTrajPipe' dif
so, I created a data type with contain all my foreignPtr.
instanciate them at the begining. this newDiffractometer function also
initialise the C library objects
c_hkl_engine_list_init engines geometry detector sample
then I just need to do a forever loop and use this type data to keep the C
internal state.
what's worring me is that I have a sort of internal state but this is not
expressed anywhere in the type system...
Cheers
Frederic
------------------------------
Message: 2
Date: Sat, 20 Feb 2016 10:57:38 +0000
From: PICCA Frederic-Emmanuel
<[email protected]>
To: "The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell" <[email protected]>
Subject: Re: [Haskell-beginners] ODP: howto Pipe
Message-ID:
<a2a20ec3b8560d408356cac2fc148e53b303b...@sun-dag3.synchrotron-soleil.fr>
Content-Type: text/plain; charset="us-ascii"
except that if I use this
runEffect $ each engines >-> solveTrajPipe factory geometry detector sample
>-> P.drain
instead of
-- >-> P.print
I get a segfault when I do a big number of coputation ???
It seems to me that the dif object is released as I am still using the
underlying foreign ptr...
------------------------------
Message: 3
Date: Sat, 20 Feb 2016 12:15:08 +0100
From: Marcin Mrotek <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] ODP: howto Pipe
Message-ID:
<CAJcfPz=O0nHbVTKL3+jEXh-wpU93ZPMYOwC18TLNkGvo6w6R=w...@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
> then I just need to do a forever loop and use this type data to keep the C
> internal state.
>
> what's worring me is that I have a sort of internal state but this is not
> expressed anywhere in the type system...
You can use (StateT <your_type> IO) instead of plain IO in the pipe to
pass that data around. There are functions for working with StateT
(and other transformer) pipes in Pipes.Lift module:
https://hackage.haskell.org/package/pipes-4.1.8/docs/Pipes-Lift.html#g:5
Other than that, having to worry about state kept in the C part of a
Haskell program is often a pain in general, unfortunately. Perhaps you
could take some hints from https://hackage.haskell.org/package/GPipe
for example, but I have no idea if that's going to be of any help.
> I get a segfault when I do a big number of coputation ???
The only change is from Pipes.print to Pipes.drain? This is weird,
maybe you'd have better luck asking on Pipes mailing list:
https://groups.google.com/forum/?fromgroups#!forum/haskell-pipes (
mailto:[email protected] )
Best regards,
Marcin Mrotek
------------------------------
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