#2473: Data.Array.IO.Internals hidden in GHC6.8 for no good reason
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Reporter: ryani | Owner:
Type: bug | Status: new
Priority: normal | Component: libraries (other)
Version: 6.8.3 | Severity: normal
Keywords: | Testcase:
Architecture: Unknown | Os: Unknown
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I had some fast array modification code in C to modify the contents of an
IOUArray, because I couldn't get my Haskell performance up to snuff. Now
that module is hidden in the array package and it doesn't seem possible to
unhide it.
The code compiled & worked quite well in GHC6.6. I understand that by
going into the internals I may have to update the code as the internals
change, but it doesn't seem to be possible to do so at all at this point.
The only workaround I can think of is to figure out the internal type from
the source, re-declare it locally, and use unsafeCoerce# shenanigans to
extract the data. That seems terrible, since future changes to the
internals could cause the code to start crashing without any compile-time
warning at all.
Bitmap.hs:
{{{
{-# OPTIONS_GHC -fffi -fglasgow-exts #-}
{-# INCLUDE "bitmap_operations.h" #-}
module Bitmap(clearBitmap) where
import Data.Array.Base
import Data.Array.IO.Internals
import GHC.Exts
import Data.Word
foreign import ccall unsafe clear_bitmap
:: MutableByteArray# RealWorld -> Word32 -> Word32 -> IO ()
{-# INLINE unsafeGetMutableArray# #-}
unsafeGetMutableArray# :: IOUArray Int Word32 -> MutableByteArray#
RealWorld
unsafeGetMutableArray# (IOUArray (STUArray _ _ array#)) = array#
clearBitmap :: IOUArray Int Word32 -> Word32 -> Word32 -> IO ()
clearBitmap a c sz = clear_bitmap (unsafeGetMutableArray# a) c sz
}}}
bitmap_operations.h:
{{{
#include "HsFFI.h"
void clear_bitmap(void* p, HsWord32 color, HsWord32 size);
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2473>
GHC <http://www.haskell.org/ghc/>
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