Safe Haskell	Safe
Language	Haskell2010

Ptr.Fun

Synopsis

data FunPtr a
nullFunPtr :: FunPtr a
castFunPtr :: FunPtr a -> FunPtr b
castFunPtrToPtr :: FunPtr a -> Ptr b
castPtrToFunPtr :: Ptr a -> FunPtr b
freeHaskellFunPtr :: FunPtr a -> IO ()
type FinalizerPtr a = FunPtr (Ptr a -> IO ())
type FinalizerEnvPtr env a = FunPtr (Ptr env -> Ptr a -> IO ())
finalizerFree :: FinalizerPtr a

Documentation

data FunPtr a #

A value of type FunPtr a is a pointer to a function callable from foreign code. The type a will normally be a foreign type, a function type with zero or more arguments where

the argument types are marshallable foreign types, i.e. Char, Int, Double, Float, Bool, Int8, Int16, Int32, Int64, Word8, Word16, Word32, Word64, Ptr a, FunPtr a, StablePtr a or a renaming of any of these using newtype.
the return type is either a marshallable foreign type or has the form IO t where t is a marshallable foreign type or ().

A value of type FunPtr a may be a pointer to a foreign function, either returned by another foreign function or imported with a a static address import like

foreign import ccall "stdlib.h &free"
  p_free :: FunPtr (Ptr a -> IO ())

or a pointer to a Haskell function created using a wrapper stub declared to produce a FunPtr of the correct type. For example:

type Compare = Int -> Int -> Bool
foreign import ccall "wrapper"
  mkCompare :: Compare -> IO (FunPtr Compare)

Calls to wrapper stubs like mkCompare allocate storage, which should be released with freeHaskellFunPtr when no longer required.

To convert FunPtr values to corresponding Haskell functions, one can define a dynamic stub for the specific foreign type, e.g.

type IntFunction = CInt -> IO ()
foreign import ccall "dynamic"
  mkFun :: FunPtr IntFunction -> IntFunction

Instances

NFData1 FunPtr	Since: deepseq-1.4.3.0
Instance details Defined in Control.DeepSeq Methods liftRnf :: (a -> ()) -> FunPtr a -> () #
Eq (FunPtr a)
Instance details Defined in GHC.Ptr Methods (==) :: FunPtr a -> FunPtr a -> Bool # (/=) :: FunPtr a -> FunPtr a -> Bool #
Ord (FunPtr a)
Instance details Defined in GHC.Ptr Methods compare :: FunPtr a -> FunPtr a -> Ordering # (<) :: FunPtr a -> FunPtr a -> Bool # (<=) :: FunPtr a -> FunPtr a -> Bool # (>) :: FunPtr a -> FunPtr a -> Bool # (>=) :: FunPtr a -> FunPtr a -> Bool # max :: FunPtr a -> FunPtr a -> FunPtr a # min :: FunPtr a -> FunPtr a -> FunPtr a #
Show (FunPtr a)	Since: base-2.1
Instance details Defined in GHC.Ptr Methods showsPrec :: Int -> FunPtr a -> ShowS # show :: FunPtr a -> String # showList :: [FunPtr a] -> ShowS #
Hashable (FunPtr a)
Instance details Defined in Data.Hashable.Class Methods hashWithSalt :: Int -> FunPtr a -> Int # hash :: FunPtr a -> Int #
Storable (FunPtr a)	Since: base-2.1
Instance details Defined in Foreign.Storable Methods sizeOf :: FunPtr a -> Int # alignment :: FunPtr a -> Int # peekElemOff :: Ptr (FunPtr a) -> Int -> IO (FunPtr a) # pokeElemOff :: Ptr (FunPtr a) -> Int -> FunPtr a -> IO () # peekByteOff :: Ptr b -> Int -> IO (FunPtr a) # pokeByteOff :: Ptr b -> Int -> FunPtr a -> IO () # peek :: Ptr (FunPtr a) -> IO (FunPtr a) # poke :: Ptr (FunPtr a) -> FunPtr a -> IO () #
NFData (FunPtr a)	Since: deepseq-1.4.2.0
Instance details Defined in Control.DeepSeq Methods rnf :: FunPtr a -> () #
Prim (FunPtr a)
Instance details Defined in Data.Primitive.Types Methods sizeOf# :: FunPtr a -> Int# # alignment# :: FunPtr a -> Int# # indexByteArray# :: ByteArray# -> Int# -> FunPtr a # readByteArray# :: MutableByteArray# s -> Int# -> State# s -> (#State# s, FunPtr a#) # writeByteArray# :: MutableByteArray# s -> Int# -> FunPtr a -> State# s -> State# s # setByteArray# :: MutableByteArray# s -> Int# -> Int# -> FunPtr a -> State# s -> State# s # indexOffAddr# :: Addr# -> Int# -> FunPtr a # readOffAddr# :: Addr# -> Int# -> State# s -> (#State# s, FunPtr a#) # writeOffAddr# :: Addr# -> Int# -> FunPtr a -> State# s -> State# s # setOffAddr# :: Addr# -> Int# -> Int# -> FunPtr a -> State# s -> State# s #

nullFunPtr :: FunPtr a #

The constant nullFunPtr contains a distinguished value of FunPtr that is not associated with a valid memory location.

castFunPtr :: FunPtr a -> FunPtr b #

Casts a FunPtr to a FunPtr of a different type.

castFunPtrToPtr :: FunPtr a -> Ptr b #

Casts a FunPtr to a Ptr.

Note: this is valid only on architectures where data and function pointers range over the same set of addresses, and should only be used for bindings to external libraries whose interface already relies on this assumption.

castPtrToFunPtr :: Ptr a -> FunPtr b #

Casts a Ptr to a FunPtr.

Note: this is valid only on architectures where data and function pointers range over the same set of addresses, and should only be used for bindings to external libraries whose interface already relies on this assumption.

freeHaskellFunPtr :: FunPtr a -> IO () #

Release the storage associated with the given FunPtr, which must have been obtained from a wrapper stub. This should be called whenever the return value from a foreign import wrapper function is no longer required; otherwise, the storage it uses will leak.

type FinalizerPtr a = FunPtr (Ptr a -> IO ()) #

A finalizer is represented as a pointer to a foreign function that, at finalisation time, gets as an argument a plain pointer variant of the foreign pointer that the finalizer is associated with.

Note that the foreign function must use the ccall calling convention.

type FinalizerEnvPtr env a = FunPtr (Ptr env -> Ptr a -> IO ()) #

finalizerFree :: FinalizerPtr a #

A pointer to a foreign function equivalent to free, which may be used as a finalizer (cf ForeignPtr) for storage allocated with malloc, mallocBytes, realloc or reallocBytes.