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7. Foreign

This module provides the ForeignObj type, which is a Haskell reference to an object in the outside world. Foreign objects are boxed versions of Addr#, the only reason for their existence is so that they can be used with finalisers (see Section Finalisation for foreign objects).

module Foreign where
data ForeignObj  -- abstract, instance of: Eq

makeForeignObj  :: Addr{-object-} -> IO ForeignObj
writeForeignObj :: ForeignObj -> Addr{-new value-} -> IO ()

In addition to the above, the following operations for indexing via a ForeignObj are also, mirrored on the same operations provided over Addrs:

indexCharOffForeignObj   :: ForeignObj -> Int -> Char
indexIntOffForeignObj    :: ForeignObj -> Int -> Int
indexAddrOffForeignObj   :: ForeignObj -> Int -> Addr
indexFloatOffForeignObj  :: ForeignObj -> Int -> Float
indexDoubleOffForeignObj :: ForeignObj -> Int -> Double
indexWord8OffForeignObj  :: ForeignObj -> Int -> Word8
indexWord16OffForeignObj :: ForeignObj -> Int -> Word16
indexWord32OffForeignObj :: ForeignObj -> Int -> Word32
indexWord64OffForeignObj :: ForeignObj -> Int -> Word64

indexInt8OffForeignObj  :: ForeignObj -> Int -> Int8
indexInt16OffForeignObj :: ForeignObj -> Int -> Int16
indexInt32OffForeignObj :: ForeignObj -> Int -> Int32
indexInt64OffForeignObj :: ForeignObj -> Int -> Int64

-- read value out of mutable memory
readCharOffForeignObj    :: ForeignObj -> Int -> IO Char
readIntOffForeignObj     :: ForeignObj -> Int -> IO Int
readAddrOffForeignObj    :: ForeignObj -> Int -> IO Addr
readFloatOffForeignObj   :: ForeignObj -> Int -> IO Float
readDoubleOffForeignObj  :: ForeignObj -> Int -> IO Double
readWord8OffForeignObj   :: ForeignObj -> Int -> IO Word8
readWord16OffForeignObj  :: ForeignObj -> Int -> IO Word16
readWord32OffForeignObj  :: ForeignObj -> Int -> IO Word32
readWord64OffForeignObj  :: ForeignObj -> Int -> IO Word64
readInt8OffForeignObj    :: ForeignObj -> Int -> IO Int8
readInt16OffForeignObj   :: ForeignObj -> Int -> IO Int16
readInt32OffForeignObj   :: ForeignObj -> Int -> IO Int32
readInt64OffForeignObj   :: ForeignObj -> Int -> IO Int64

writeCharOffForeignObj   :: ForeignObj -> Int -> Char   -> IO ()
writeIntOffForeignObj    :: ForeignObj -> Int -> Int    -> IO ()
writeAddrOffForeignObj   :: ForeignObj -> Int -> Addr   -> IO ()
writeFloatOffForeignObj  :: ForeignObj -> Int -> Float  -> IO ()
writeDoubleOffForeignObj :: ForeignObj -> Int -> Double -> IO ()
writeWord8OffForeignObj  :: ForeignObj -> Int -> Word8  -> IO ()
writeWord16OffForeignObj :: ForeignObj -> Int -> Word16 -> IO ()
writeWord32OffForeignObj :: ForeignObj -> Int -> Word32 -> IO ()
writeWord64OffForeignObj :: ForeignObj -> Int -> Word64 -> IO ()
writeInt8OffForeignObj   :: ForeignObj -> Int -> Int8   -> IO ()
writeInt16OffForeignObj  :: ForeignObj -> Int -> Int16  -> IO ()
writeInt32OffForeignObj  :: ForeignObj -> Int -> Int32  -> IO ()
writeInt64OffForeignObj  :: ForeignObj -> Int -> Int64  -> IO ()


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