Re: again: nullForeignPtr
Alastair Reid <[email protected]>
| Newsgroups | gmane.comp.lang.haskell.ffi |
|---|---|
| Organization | Reid-Hoffmann |
| Message-ID | <[email protected]> |
> The need for nullForeignPtr arises when a function expects > a pointer to some data structure or a null pointer. In this case I cannot > make the foreign import have the type (Maybe (ForeignPtr ()) since it's not > accepted by the FFI. I guess I've mostly used this trick with GreenCard whcih supports this idiom quite well. Mind you, ForeignPtr isn't accepted by the FFI either so the code you currently use to marshall them could be modified to marshall Maybe (ForeignPtr ()) instead. -- Alastair