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Today's Topics:
1. Storable which is only Peekable (PICCA Frederic-Emmanuel)
----------------------------------------------------------------------
Message: 1
Date: Sun, 4 Aug 2019 09:57:28 +0000
From: PICCA Frederic-Emmanuel
<frederic-emmanuel.pi...@synchrotron-soleil.fr>
To: "The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell" <beginners@haskell.org>
Subject: [Haskell-beginners] Storable which is only Peekable
Message-ID:
<a2a20ec3b8560d408356cac2fc148e53016cf45...@sun-dag3.synchrotron-soleil.fr>
Content-Type: text/plain; charset="us-ascii"
Hello, I would like to know what is the best way to create a type which is
only peekable and pokable.
When I use Storable, I "need" to define peek and poke and ghc complain that I
did not defined the poke part.
So how can I write something nice.
Cheers
Frederic
#include "hkl-binoculars.h"
data Space = Space (ForeignPtr Space) Int
deriving Show
foreign import ccall safe "fromImage" c_fromImage :: Ptr Double -> Int -> Ptr
Double -> Ptr Int -> Int -> Ptr Word16 -> Ptr Int -> Int -> IO (Ptr Space)
foreign import ccall unsafe "&space_free" c_space_free :: FunPtr (Ptr Space ->
IO ())
instance Storable Space where
alignment _ = #{alignment struct space_t}
sizeOf _ = #{size struct space_t}
peek ptr = Space
<$> newForeignPtr c_space_free ptr
<*> #{peek struct space_t, ndim} ptr
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