Le mercredi 29 septembre 2010 18:00:20, Simon Marlow a écrit :
On 29/09/10 04:54, Mathieu Giorgino wrote:
Hi all,
I'm wondering if there is a way to get an hashcode from references (IORef or STRef)? I have looked in the library and a little in the sources of GHC but haven't found anything allowing to do this.
I'm generating Haskell code from the Isabelle/HOL proof assistant, which generate "generic" code for other langages too which all have this notion, and I would so need an equivalent in Haskell.
Have you any hint on how to achieve this, or even if it is possible?
IORefs themselves have no persistent properties that could be used to make a hash value, so you would have to implement this yourself on top of IORef, perhaps using Data.Unique for example. Something like this:
data IdIORef a = IdIORef Unique !(IORef a)
newIdIORef :: a -> IO (IdIORef a) newIdIORef a = do u <- getUnique r <- newIORef a return (IdIORef u r)
Cheers, Simon
Great, I will dig into this direction. Thanks a lot, Mathieu