Alastair wrote [snip]

makeForeignPtr :: Ptr a -> FunPtr (Ptr a -> IO ()) -> IO ForeignObj

[snip] I don't understand this proposal. What is a ForeignObj?

Sorry, that was a typo. The result type should be IO (ForeignPtr a)

I call a C function, which gives me a cString :: Ptr CChar, and it's my responsibility to free it when I've finished with it. So I convert it to a ForeignPtr:

foreignPtr <- mkForeignPtr cString

and then always refer to the pointer via foreignPtr. When foreignPtr is garbage collected the space is freed. So how do I do this with your proposal?

With the existing spec, you would write:

foreign import free :: Ptr CChar -> IO ()

foo = do ... foreignPtr <- newForeignPtr cString (free cString) ...

With my proposal, you would write:

foreign import "&" free :: FunPtr (Ptr CChar -> IO ())

foo = do ... foreignPtr <- newForeignPtr cString free ...

All the rest of your code to manipulate ForeignPtrs remains the same. (Well, there's a corresponding change in addForeignFinalizer if you happen to use that.) -- Alastair Reid alastair@reid-consulting-uk.ltd.uk Reid Consulting (UK) Limited http://www.reid-consulting-uk.ltd.uk/alastair/