[Haskell-Cafe] FFI and foreign function returning a structure
Ben Lippmeier
Ben.Lippmeier at anu.edu.au
Tue Mar 1 22:45:54 EST 2005
Dimitry Golubovsky wrote:
> Hi,
>
> If I have a C function returning a structure (not a pointer, but
> structure itself), can this be accomodated via FFI?
No. The way data is organised in memory is dramatically different in
Haskell when compared with C. You need to write functions to read in
each field in turn and then "reconstruct" the structure on the Haskell
side.
It's a tedious process. My advice is that if you have a lot of
structures to read, write a (simple) preprocessor to generate the
marshalling code.. that's what I did.
Ben.
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