[Haskell-cafe] FFI and pointers to pointers

Simon Marlow simonmar at microsoft.com
Mon Apr 25 07:51:04 EDT 2005

On 22 April 2005 16:18, Dimitry Golubovsky wrote:

> I am trying to generalize my knowledge about FFI declarations when
> dealing with pointers to pointers (import from C to Haskell). Maybe
> these are silly questions, but It seems to me, I am missing some
> understanding.
> Per the FFI Addendum:
> For a variable, we use "&" import:
> int bar;
> foreign import ccall "&" bar :: Ptr CInt

The syntax you want is

  foreign import ccall "&bar" :: Ptr CInt

But note that GHC 6.4 has a bug whereby this doesn't work as expected
when compiling via C.  Either use the native code generator (-fasm) or
wait for 6.4.1.


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