Array inside a struct ....

gistfile1.txt

{-# LANGUAGE CPP #-}
module CHSTest where
import Control.Monad
import Foreign
import Foreign.C
import Foreign.Ptr
#c
typedef struct {
  int x;
} A;
typedef struct {
  A* as;
} B;
#endc
{#pointer *A as APtr newtype #}
{#pointer *B as BPtr newtype #}
data MyA = MyA {
             x :: CInt
           }
data MyB = MyB {
             as :: [MyA]
          }
instance Storable MyA where
    sizeOf _ = {# sizeof A #}
    alignment _ = {# alignof A #}
    poke p a = {#set A->x #} p (x a)
    peek p = do
      x' <- {#get A->x #} p
      return $ MyA x'

instance Storable MyB where
    sizeOf _ = {# sizeof B #}
    alignment _ = {# alignof B #}
    poke p b = do
      ptr <- mallocArray (length $ as b)
      pokeArray ptr (as b)
      {#set B->as #} p ptr
    peek _ = undefined

-- compiler error
src/CHSTest.chs:36:60:
    Couldn't match expected type `APtr' with actual type `Ptr MyA'
    In the second argument of `\ ptr val
                                 -> do { pokeByteOff ptr 0 (val :: APtr) }', namely
      `ptr'
    In a stmt of a 'do' block:
      (\ ptr val -> do { pokeByteOff ptr 0 (val :: APtr) }) p ptr
    In the expression:
      do { ptr <- mallocArray (length $ as b);
           pokeArray ptr (as b);
           (\ ptr val -> do { pokeByteOff ptr 0 (val :: APtr) }) p ptr }

-- Generated Output
-- GENERATED by C->Haskell Compiler, version 0.16.5 Crystal Seed, 24 Jan 2009 (Haskell)
-- Edit the ORIGNAL .chs file instead!


{-# LINE 1 "src/CHSTest.chs" #-}{-# LANGUAGE CPP #-}
module CHSTest where
import Control.Monad
import Foreign
import Foreign.C
import Foreign.Ptr
type APtr = ForeignPtr (MyA)
{-# LINE 15 "src/CHSTest.chs" #-}
newtype BPtr = BPtr (Ptr (BPtr))
{-# LINE 16 "src/CHSTest.chs" #-}
data MyA = MyA {
             x :: CInt
           }
data MyB = MyB {
             as :: [MyA]
          }
instance Storable MyA where
    sizeOf _ = 4
{-# LINE 24 "src/CHSTest.chs" #-}
    alignment _ = 4
{-# LINE 25 "src/CHSTest.chs" #-}
    poke p a = (\ptr val -> do {pokeByteOff ptr 0 (val::CInt)}) p (x a)
    peek p = do
      x' <- (\ptr -> do {peekByteOff ptr 0 ::IO CInt}) p
      return $ MyA x'

instance Storable MyB where
    sizeOf _ = 8
{-# LINE 32 "src/CHSTest.chs" #-}
    alignment _ = 8
{-# LINE 33 "src/CHSTest.chs" #-}
    poke p b = do
      ptr <- mallocArray (length $ as b)
      pokeArray ptr (as b)
      (\ptr val -> do {pokeByteOff ptr 0 (val::(Ptr (MyA)))}) p ptr
    peek _ = undefined