I suggest you implement
hashTypeable :: Typeable -> IO Int32
Lennart wrote (snipped)
And/or
mkHashTypeable :: IO (Typeable -> Int32)
Although this is OK, a general hash function might well need to return IO HashKey.
A while back, before Data.Unique, I implemented a Unique module with interface:
newUnique :: IO Unique uniqCompare :: Unique -> Unique -> IO Ordering
The values returned by uniqCompare are guaranteed to be consistent. This implementation (which was not meant terribly seriously) was unusual because it did not use unsafePerformIO or any other global state, though it did need MVars and access to the current thread identifier (if in a concurrent world). The ordering was constructed dynamically as you called uniqCompare. The source is here:
http://www.mail-archive.com/glasgow-haskell-users@haskell.org/msg01109/Unique.hs
Converting the function to be of type
getUniqCompare :: IO (Unique -> Unique -> Ordering)
would be impossible. I suspect there may be other cases where you dynamically construct a hash function. _______________________________________________ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
