Re: [Haskell-cafe] Storables and Ptrs

This can be used to call into C code expecting pointer input or output types to great effect:

wrapperAroundForeignCode :: InputType -> IO OutputType wrapperAroundForeignCode in =  alloca $ \inPtr ->  alloca $ outPtr -> do    poke inPtr in    c_call inPtr outPtr    peek outPtr

There is also 'with' (:: Storable a => a -> (Ptr a -> IO b) -> IO b), which is exactly the combination of 'alloca' and 'poke' you use on 'in'. Erik