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Today's Topics:
1. Strorable and incomplete type (PICCA Frederic-Emmanuel)
----------------------------------------------------------------------
Message: 1
Date: Mon, 27 Jun 2016 16:49:46 +0000
From: PICCA Frederic-Emmanuel
<frederic-emmanuel.pi...@synchrotron-soleil.fr>
To: "beginners@haskell.org" <beginners@haskell.org>
Subject: [Haskell-beginners] Strorable and incomplete type
Message-ID:
<a2a20ec3b8560d408356cac2fc148e53b307f...@sun-dag3.synchrotron-soleil.fr>
Content-Type: text/plain; charset="Windows-1252"
Hello,
I would like to use Storable and declare an instance for a struct available in
a C library
instance Storable Parameter where
sizeOf _ = #{size HklParameter}
peek ptr = alloca $ \pmin ->
alloca $ \pmax -> do
cname <- c_hkl_parameter_name_get ptr
name <- peekCString cname
value <- c_hkl_parameter_value_get ptr unit
c_hkl_parameter_min_max_get ptr pmin pmax unit
min <- peek pmin
max <- peek pmax
return (Parameter name value (Range min max))
but when I try to compile this, I get this error message
C.hsc:507:15: error: invalid application of ‘sizeof’ to incomplete type
‘HklParameter’
Indeed the C library do not expose this struct internal.
So I would like to know how to handle this kind of C struct with Storable.
thanks for your help
Frédéric
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