Re: [Haskell-cafe] Types and hashes of hashes, trouble for a Java-programmer...

Yes, got the point. But is it not possible to "wrap IO inside IO" at all? What would the program look like, just for the exercise? On Mon, Apr 13, 2009 at 6:50 PM, Lennart Augustsson wrote:

No, removing IO is the right way.  There is no reason to involve IO for this.

 -- Lennart

On Mon, Apr 13, 2009 at 6:27 PM, John Smith wrote:

...

If you mean using a non-destructive map where the IO-problem is absent, that is a doable thing. But it would be like cheating :-)

What I try do do is something like:

test = do   h <- HashTable.new (==) (\key -> key)   h1 <- HashTable.new (==) (\key -> key)   HashTable.insert h 3 h1   HashTable.insert h1 1 1000   res <- case HashTable.lookup h 3 of       Nothing -> Nothing       Just outer -> HashTable.lookup outer 1000   return res _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe