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Today's Topics:
1. Re: FFI foreignPtr construction (Sylvain Henry)
2. Is it possible to use a <> constructor in analogy to [] ?
(martin)
3. Re: FFI foreignPtr construction (PICCA Frederic-Emmanuel)
4. Re: Increasing capabilities dramatically increases execution
time (Thomas Koster)
----------------------------------------------------------------------
Message: 1
Date: Wed, 27 Jan 2016 19:37:00 +0100
From: Sylvain Henry <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] FFI foreignPtr construction
Message-ID:
<capmptcw1rayvdgyt7dgdbhpaoa+rko3zxzs26c3-uybcceq...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Hi,
You can try something like this (not tested):
data Geo = Geo -- this represents the HklGeometry C structure (for clarity)
newtype Geometry = Geometry (ForeignPtr Geo) deriving (Show, Storable)
newGeometry :: Factory -> IO Geometry
newGeometry f = do -- avoid unsafePerformIO
geometry <- c_hkl_factory_create_new_geometry f
Geometry <$> newForeignPtr c_hkl_geometry_free geometry
foreign import ccall safe "hkl.h hkl_factory_create_new_geometry"
c_hkl_factory_create_new_geometry :: Factory
-> IO (Ptr Geo)
foreign import ccall safe "hkl.h &hkl_geometry_free"
c_hkl_geometry_free :: FunPtr (Ptr Geo -> IO ())
2016-01-27 13:50 GMT+01:00 PICCA Frederic-Emmanuel <
[email protected]>:
> Hello,
>
> since the last time I think that I understand how to manage Ptr, now I
> woud like to masterize the ForeignPtr in order to let haskell managed the
> life of my C objects.
> So I try to create a Geoemtry object like this.
>
> -- data Geometry
> newtype Geometry = Geometry (Ptr Geometry) deriving (Show, Storable)
>
> newGeometry :: Factory -> ForeignPtr Geometry
> newGeometry f = unsafePerformIO $ do
> geometry <- c_hkl_factory_create_new_geometry f
> newForeignPtr c_hkl_geometry_free geometry
>
> foreign import ccall safe "hkl.h hkl_factory_create_new_geometry"
> c_hkl_factory_create_new_geometry :: Factory
> -> IO (Geometry)
>
> foreign import ccall safe "hkl.h &hkl_geometry_free"
> c_hkl_geometry_free :: FunPtr (Geometry -> IO ())
>
>
>
> the C signature are
>
> HKLAPI HklGeometry *hkl_factory_create_new_geometry(const HklFactory
> *self) HKL_ARG_NONNULL(1);
>
> HKLAPI void hkl_geometry_free(HklGeometry *self) HKL_ARG_NONNULL(1);
>
>
> But when I try to compile this code, I get this error message
>
>
> 1 of 1] Compiling Hkl.C ( src/Hkl/C.hs, dist/build/Hkl/C.o )
>
> src/Hkl/C.hs:51:33:
> Couldn't match type ?Geometry? with ?Ptr Geometry?
> Expected type: GHC.ForeignPtr.FinalizerPtr Geometry
> Actual type: FunPtr (Geometry -> IO ())
> In the first argument of ?newForeignPtr?, namely
> ?c_hkl_geometry_free?
> In a stmt of a 'do' block:
> newForeignPtr c_hkl_geometry_free geometry
>
> src/Hkl/C.hs:51:53:
> Couldn't match expected type ?Ptr Geometry?
> with actual type ?Geometry?
> In the second argument of ?newForeignPtr?, namely ?geometry?
> In a stmt of a 'do' block:
> newForeignPtr c_hkl_geometry_free geometry
>
> I do not understand what is wrong in my code
>
> thanks if you can help
>
> Frederic
> _______________________________________________
> Beginners mailing list
> [email protected]
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>
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------------------------------
Message: 2
Date: Wed, 27 Jan 2016 21:40:18 +0100
From: martin <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: [Haskell-beginners] Is it possible to use a <> constructor in
analogy to [] ?
Message-ID: <[email protected]>
Content-Type: text/plain; charset=utf-8
Hello all,
I've written my own Read and Show instances for a type, which is essentially
data Crust a = Open [a] | Closed [a]
"Show" does something like
*Main> Closed [1,2,3]
<1,2,3>
*Main> Open [1,2,3]
<1,2,3..>
And Read faithully parses each stings and turns it into a Crust again.
Problem is: when I just type <1,2,3..> in GHCi I get a "parse error on input
?<?". However when I spell out the
custructor as above it parses it okay.
Is it possible at all to write my own <> constructor, or something like it=
------------------------------
Message: 3
Date: Wed, 27 Jan 2016 20:49:22 +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] FFI foreignPtr construction
Message-ID:
<a2a20ec3b8560d408356cac2fc148e53b3028...@sun-dag3.synchrotron-soleil.fr>
Content-Type: text/plain; charset="us-ascii"
Thanks for your help
I end up with this code which I find quite elegant :)
-- data Geometry
data HklGeometry
newtype Geometry = Geometry (ForeignPtr HklGeometry) deriving (Show)
newGeometry :: Factory -> IO Geometry
newGeometry f =
Geometry <$> (c_hkl_factory_create_new_geometry f >>= newForeignPtr
c_hkl_geometry_free)
foreign import ccall unsafe "hkl.h hkl_factory_create_new_geometry"
c_hkl_factory_create_new_geometry :: Factory -> IO (Ptr HklGeometry)
foreign import ccall unsafe "hkl.h &hkl_geometry_free"
c_hkl_geometry_free :: FunPtr (Ptr HklGeometry -> IO ())
Cheers
Frederic
------------------------------
Message: 4
Date: Thu, 28 Jan 2016 11:06:55 +1100
From: Thomas Koster <[email protected]>
To: [email protected]
Subject: Re: [Haskell-beginners] Increasing capabilities dramatically
increases execution time
Message-ID:
<cag1wh7coaj4hwom377rj42ryt-cmj4om191fphs+q10ltau...@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
> On 2016-01-22, Thomas Koster wrote:
> I have encountered a situation in a concurrent program where I see an
> unexpected, dramatic increase in execution time when I add additional
> capabilities. On a multi-core CPU, "-N1" is fastest by an order of
> magnitude and the program increasingly slows for an increasing number
> of capabilities (still fewer than the number of real cores, of
> course).
>
> <snip/>
On 27 January 2016 at 18:07, Elias Diem <[email protected]> wrote:
> Maybe post this to the caf? list at:
>
> https://mail.haskell.org/mailman/listinfo/haskell-cafe
Thanks, Elias. This is being discussed there in the thread "When are
MVars better than STM?".
https://mail.haskell.org/pipermail/haskell-cafe/2016-January/122785.html
--
Thomas Koster
------------------------------
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