Scott Turner wrote:
On 2005 June 02 Thursday 04:38, Gracjan Polak wrote:
iorefset :: Ord a => IORef(Map.Map a a) iorefset = unsafePerformIO $ do newIORef $ Map.empty
I could have as many dictionaries as there are types. The problem is I get one dictionary for each object which defeats the idea.
To avoid unsafe operations and get control over the dictionaries that are created, I would put the desired dictionaries into a state monad. The type of 'intern' becomes Ord a => a -> DictionaryState a All the code that uses 'intern' would need some modification to deal more directly with the dictionary state. It may be more complex, but it's also more solid.
As intern behaves like id and does not have any side effects, I thought its interface should be purely functional. But I do not see any way to do it :( I'll end up with a monad, probably. In related question: does anybody here have experience/benchmarks/tests how/if is PackedString better (uses less memory) than String in parsing tasks? -- Gracjan