Haskell Hierarchical Libraries (base package)ContentsIndex
GHC.Ptr
Portability non-portable (GHC Extensions)
Stability internal
Maintainer ffi@haskell.org
Description
The Ptr and FunPtr types and operations.
Synopsis
data Ptr a = Ptr 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
data FunPtr a = FunPtr Addr#
nullFunPtr :: FunPtr a
castFunPtr :: FunPtr a -> FunPtr b
castFunPtrToPtr :: FunPtr a -> Ptr b
castPtrToFunPtr :: Ptr a -> FunPtr b
Documentation
data Ptr a

A value of type Ptr a represents a pointer to an object, or an array of objects, which may be marshalled to or from Haskell values of type a.

The type a will normally be an instance of class Storable which provides the marshalling operations.

Constructors
Ptr Addr#
Instances
IArray UArray (Ptr a)
Ix ix => Eq (UArray ix (Ptr a))
Ix ix => Ord (UArray ix (Ptr a))
MArray (STUArray s) (Ptr a) (ST s)
IArray (IOToDiffArray IOUArray) (Ptr a)
MArray IOUArray (Ptr a) IO
Typeable a => Typeable (Ptr a)
Show (Ptr a)
Storable (Ptr a)
Eq (Ptr a)
Ord (Ptr a)
nullPtr :: Ptr a
The constant nullPtr contains a distinguished value of Ptr that is not associated with a valid memory location.
castPtr :: Ptr a -> Ptr b
The castPtr function casts a pointer from one type to another.
plusPtr :: Ptr a -> Int -> Ptr b
Advances the given address by the given offset in bytes.
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 first to the second argument. We have

 p2 == p1 `plusPtr` (p2 `minusPtr` p1)
data FunPtr a

A value of type FunPtr a is a pointer to a piece of code. It may be the pointer to a C function or to a Haskell function created using foreign export dynamic. A foreign export dynamic should normally be declared to produce a FunPtr of the correct type. For example:

 type Compare = Int -> Int -> Bool
 foreign export dynamic mkCompare :: Compare -> IO (FunPtr Compare)
Constructors
FunPtr Addr#
Instances
IArray UArray (FunPtr a)
Ix ix => Eq (UArray ix (FunPtr a))
Ix ix => Ord (UArray ix (FunPtr a))
MArray (STUArray s) (FunPtr a) (ST s)
IArray (IOToDiffArray IOUArray) (FunPtr a)
MArray IOUArray (FunPtr a) IO
Show (FunPtr a)
Storable (FunPtr a)
Eq (FunPtr a)
Ord (FunPtr a)
nullFunPtr :: FunPtr a
The constant nullFunPtr contains a distinguished value of Ptr 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
castPtrToFunPtr :: Ptr a -> FunPtr b
Casts a Ptr to a FunPtr
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