Serious Data.HashTable bug

The program below illustrates a difference between the description of the semantics of insert (given below) and the implementation. Try calling the function "test" with values greater than 2047. For instance:

HT> test 2048 0 1024

The documentation states: insert :: HashTable key val -> key -> val -> IO ()

Inserts an key/value mapping into the hash table.

Note that insert doesn't remove the old entry from the table

• the behaviour is like an association list, where lookup returns the most-recently-inserted mapping for a key in the table. The reason for this is to keep insert as efficient as possible. If you need to update a mapping, then we provide update.

module HT where

import Data.HashTable
import qualified Data.HashTable as HT

test :: Int -> IO ()
test n = do ht <- new (==) hashInt
            sequence_ [ insert ht key 0 | key <- [0..n]]
            sequence_ [ insert ht key 1 | key <- [0..n]]
          
            let check key = do (Just val) <- HT.lookup ht key
                               if val==1 then return () else putStrLn $ show key 
          
            sequence_ [ check key | key <- [0..n]]

Trac metadata

Trac field	Value
Version	6.4.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	high
Resolution	Unresolved
Component	libraries/base
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system	Unknown
Architecture	Unknown