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

[Lennart Augustsson]

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 <smithsnorth at gmail.com> 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
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