Re: [Haskell-cafe] Simple hash table creation

Look in Data.Int for a list of the Int types. Basically you generally only use Int unless you are working at a lower- level which has an explicit requirement for the number of bits. In this case, HashTable has such a requirement, so you have two choices: you can either change the type annotation on dummy: import Data.Int dummy:: String -> Int32 dummy s = 7 or you can just leave it off entirely, and GHC will automatically infer the correct type (without you needing to import Data.Int): dummy s = 7 On Nov 17, 2009, at 12:09 PM, michael rice wrote:

Hi Daniel,

Thanks for the IO monad reminder.

What is GHC.Int.Int32? Can't find it on Hoogle.

Michael

==================

*Main> ht <- new (==) dummy :: IO MyHashTable

<interactive>:1:15: Couldn't match expected type `GHC.Int.Int32' against inferred type `Int' In the second argument of `new', namely `dummy' In a stmt of a 'do' expression: ht <- new (==) dummy :: IO MyHashTable *Main> :t dummy dummy :: String -> Int *Main>

--- On Tue, 11/17/09, Daniel Fischer wrote:

From: Daniel Fischer Subject: Re: [Haskell-cafe] Simple hash table creation To: haskell-cafe@haskell.org Date: Tuesday, November 17, 2009, 2:45 PM

Am Dienstag 17 November 2009 20:36:46 schrieb Daniel Fischer:

...

What you probably wanted was

type MyHashTable = HashTable String Int -- not data MyHashTable

Just in case it's not clear:

...

ht <- new (==) dummy :: IO MyHashTable

only works at the prompt or in an IO do-block, not at the top level of the module.

...

then ht is a hashtable of type MyHashTable.

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