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
_______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
