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 |