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|
{-# LANGUAGE Unsafe #-}
{-# LANGUAGE NoImplicitPrelude #-}
-----------------------------------------------------------------------------
-- |
-- Module : Foreign.Marshal.Unsafe
-- Copyright : (c) The FFI task force 2003
-- License : BSD-style (see the file libraries/base/LICENSE)
--
-- Maintainer : ffi@haskell.org
-- Stability : provisional
-- Portability : portable
--
-- Marshalling support. Unsafe API.
--
-----------------------------------------------------------------------------
module Foreign.Marshal.Unsafe (
-- * Unsafe functions
unsafeLocalState
) where
import GHC.IO
{- |
Sometimes an external entity is a pure function, except that it passes
arguments and/or results via pointers. The function
@unsafeLocalState@ permits the packaging of such entities as pure
functions.
The only IO operations allowed in the IO action passed to
@unsafeLocalState@ are (a) local allocation (@alloca@, @allocaBytes@
and derived operations such as @withArray@ and @withCString@), and (b)
pointer operations (@Foreign.Storable@ and @Foreign.Ptr@) on the
pointers to local storage, and (c) foreign functions whose only
observable effect is to read and/or write the locally allocated
memory. Passing an IO operation that does not obey these rules
results in undefined behaviour.
It is expected that this operation will be
replaced in a future revision of Haskell.
-}
unsafeLocalState :: IO a -> a
unsafeLocalState = unsafeDupablePerformIO
|
