| Copyright | (c) The FFI Task Force 2000-2002 |
|---|---|
| License | see libraries/base/LICENSE |
| Maintainer | ffi@haskell.org |
| Stability | internal |
| Portability | non-portable (GHC Extensions) |
| Safe Haskell | Unsafe |
| Language | Haskell2010 |
GHC.Ptr
Contents
Synopsis
- data Ptr a = Ptr Addr#
- data FunPtr a = FunPtr Addr#
- nullPtr :: Ptr a
- castPtr :: Ptr a -> Ptr b
- plusPtr :: Ptr a -> Int -> Ptr b
- alignPtr :: Ptr a -> Int -> Ptr a
- minusPtr :: Ptr a -> Ptr b -> Int
- nullFunPtr :: FunPtr a
- castFunPtr :: FunPtr a -> FunPtr b
- castFunPtrToPtr :: FunPtr a -> Ptr b
- castPtrToFunPtr :: Ptr a -> FunPtr b
Documentation
A value of type represents a pointer to an object, or an
array of objects, which may be marshalled to or from Haskell values
of type Ptr aa.
The type a will often be an instance of class
Storable which provides the marshalling operations.
However this is not essential, and you can provide your own operations
to access the pointer. For example you might write small foreign
functions to get or set the fields of a C struct.
Instances
| Generic1 (URec (Ptr ()) :: k -> Type) # | |
| Data a => Data (Ptr a) # | Since: base-4.8.0.0 |
Defined in Data.Data Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Ptr a -> c (Ptr a) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Ptr a) # dataTypeOf :: Ptr a -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Ptr a)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Ptr a)) # gmapT :: (forall b. Data b => b -> b) -> Ptr a -> Ptr a # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Ptr a -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Ptr a -> r # gmapQ :: (forall d. Data d => d -> u) -> Ptr a -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Ptr a -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Ptr a -> m (Ptr a) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Ptr a -> m (Ptr a) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Ptr a -> m (Ptr a) # | |
| Foldable (UAddr :: Type -> Type) # | Since: base-4.9.0.0 |
Defined in Data.Foldable Methods fold :: Monoid m => UAddr m -> m # foldMap :: Monoid m => (a -> m) -> UAddr a -> m # foldMap' :: Monoid m => (a -> m) -> UAddr a -> m # foldr :: (a -> b -> b) -> b -> UAddr a -> b # foldr' :: (a -> b -> b) -> b -> UAddr a -> b # foldl :: (b -> a -> b) -> b -> UAddr a -> b # foldl' :: (b -> a -> b) -> b -> UAddr a -> b # foldr1 :: (a -> a -> a) -> UAddr a -> a # foldl1 :: (a -> a -> a) -> UAddr a -> a # elem :: Eq a => a -> UAddr a -> Bool # maximum :: Ord a => UAddr a -> a # minimum :: Ord a => UAddr a -> a # | |
| Traversable (UAddr :: Type -> Type) # | Since: base-4.9.0.0 |
| Storable (Ptr a) # | Since: base-2.1 |
| Show (Ptr a) # | Since: base-2.1 |
| Eq (Ptr a) # | Since: base-2.1 |
| Ord (Ptr a) # | Since: base-2.1 |
Defined in GHC.Ptr | |
| Functor (URec (Ptr ()) :: Type -> Type) # | Since: base-4.9.0.0 |
| Generic (URec (Ptr ()) p) # | |
| Eq (URec (Ptr ()) p) # | Since: base-4.9.0.0 |
| Ord (URec (Ptr ()) p) # | Since: base-4.9.0.0 |
Defined in GHC.Generics Methods compare :: URec (Ptr ()) p -> URec (Ptr ()) p -> Ordering Source # (<) :: URec (Ptr ()) p -> URec (Ptr ()) p -> Bool Source # (<=) :: URec (Ptr ()) p -> URec (Ptr ()) p -> Bool Source # (>) :: URec (Ptr ()) p -> URec (Ptr ()) p -> Bool Source # (>=) :: URec (Ptr ()) p -> URec (Ptr ()) p -> Bool Source # max :: URec (Ptr ()) p -> URec (Ptr ()) p -> URec (Ptr ()) p Source # min :: URec (Ptr ()) p -> URec (Ptr ()) p -> URec (Ptr ()) p Source # | |
| data URec (Ptr ()) (p :: k) # | Used for marking occurrences of Since: base-4.9.0.0 |
| type Rep1 (URec (Ptr ()) :: k -> Type) # | Since: base-4.9.0.0 |
Defined in GHC.Generics | |
| type Rep (URec (Ptr ()) p) # | Since: base-4.9.0.0 |
Defined in GHC.Generics | |
A value of type is a pointer to a function callable
from foreign code. The type FunPtr aa 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,,Ptra,FunPtraor a renaming of any of these usingStablePtranewtype. - the return type is either a marshallable foreign type or has the form
whereIOttis a marshallable foreign type or().
A value of type may be a pointer to a foreign function,
either returned by another foreign function or imported with a
a static address import likeFunPtr a
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
| Storable (FunPtr a) # | Since: base-2.1 |
Defined in Foreign.Storable | |
| Show (FunPtr a) # | Since: base-2.1 |
| Eq (FunPtr a) # | |
| Ord (FunPtr a) # | |
Defined in GHC.Ptr | |
alignPtr :: Ptr a -> Int -> Ptr a #
Given an arbitrary address and an alignment constraint,
alignPtr yields the next higher address that fulfills the
alignment constraint. An alignment constraint x is fulfilled by
any address divisible by x. This operation is idempotent.
minusPtr :: Ptr a -> Ptr b -> Int #
Computes the offset required to get from the second to the first argument. We have
p2 == p1 `plusPtr` (p2 `minusPtr` p1)
nullFunPtr :: FunPtr a #
The constant nullFunPtr contains a
distinguished value of FunPtr that is not
associated with a valid memory location.
Unsafe functions
castFunPtrToPtr :: FunPtr a -> Ptr b #