base-4.2.0.0: Basic librariesSource codeContentsIndex
Foreign.Marshal.Alloc
Portabilityportable
Stabilityprovisional
Maintainerffi@haskell.org
Contents
Memory allocation
Local allocation
Dynamic allocation
Description
Marshalling support: basic routines for memory allocation
Synopsis
alloca :: Storable a => (Ptr a -> IO b) -> IO b
allocaBytes :: Int -> (Ptr a -> IO b) -> IO b
malloc :: Storable a => IO (Ptr a)
mallocBytes :: Int -> IO (Ptr a)
realloc :: Storable b => Ptr a -> IO (Ptr b)
reallocBytes :: Ptr a -> Int -> IO (Ptr a)
free :: Ptr a -> IO ()
finalizerFree :: FinalizerPtr a
Memory allocation
Local allocation
alloca :: Storable a => (Ptr a -> IO b) -> IO bSource

alloca f executes the computation f, passing as argument a pointer to a temporarily allocated block of memory sufficient to hold values of type a.

The memory is freed when f terminates (either normally or via an exception), so the pointer passed to f must not be used after this.

allocaBytes :: Int -> (Ptr a -> IO b) -> IO bSource

allocaBytes n f executes the computation f, passing as argument a pointer to a temporarily allocated block of memory of n bytes. The block of memory is sufficiently aligned for any of the basic foreign types that fits into a memory block of the allocated size.

The memory is freed when f terminates (either normally or via an exception), so the pointer passed to f must not be used after this.

Dynamic allocation
malloc :: Storable a => IO (Ptr a)Source

Allocate a block of memory that is sufficient to hold values of type a. The size of the area allocated is determined by the sizeOf method from the instance of Storable for the appropriate type.

The memory may be deallocated using free or finalizerFree when no longer required.

mallocBytes :: Int -> IO (Ptr a)Source

Allocate a block of memory of the given number of bytes. The block of memory is sufficiently aligned for any of the basic foreign types that fits into a memory block of the allocated size.

The memory may be deallocated using free or finalizerFree when no longer required.

realloc :: Storable b => Ptr a -> IO (Ptr b)Source

Resize a memory area that was allocated with malloc or mallocBytes to the size needed to store values of type b. The returned pointer may refer to an entirely different memory area, but will be suitably aligned to hold values of type b. The contents of the referenced memory area will be the same as of the original pointer up to the minimum of the original size and the size of values of type b.

If the argument to realloc is nullPtr, realloc behaves like malloc.

reallocBytes :: Ptr a -> Int -> IO (Ptr a)Source

Resize a memory area that was allocated with malloc or mallocBytes to the given size. The returned pointer may refer to an entirely different memory area, but will be sufficiently aligned for any of the basic foreign types that fits into a memory block of the given size. The contents of the referenced memory area will be the same as of the original pointer up to the minimum of the original size and the given size.

If the pointer argument to reallocBytes is nullPtr, reallocBytes behaves like malloc. If the requested size is 0, reallocBytes behaves like free.

free :: Ptr a -> IO ()Source
Free a block of memory that was allocated with malloc, mallocBytes, realloc, reallocBytes, Foreign.Marshal.Utils.new or any of the newX functions in Foreign.Marshal.Array or Foreign.C.String.
finalizerFree :: FinalizerPtr aSource
A pointer to a foreign function equivalent to free, which may be used as a finalizer (cf Foreign.ForeignPtr.ForeignPtr) for storage allocated with malloc, mallocBytes, realloc or reallocBytes.
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