[Haskell-cafe] Bug in writeArray?

[Grzegorz Chrupała]

Hi all,
This seems like a bug in the implementation of writeArray: when passed
an out-of-range index it silently writes to an incorrect index in the
array.
--

import Data.Array.IO
import Data.Array.Unboxed

main = do
  let (l,u) = ((0,10),(20,20))
  marr <- newArray (l,u) 0 :: IO (IOUArray (Int,Int) Int)
  let badi = (10,9)
  print (inRange (l,u) badi)
  writeArray marr badi 1
  arr <- freeze marr :: IO (UArray (Int,Int) Int)
  print . filter ((/=0) . snd) . assocs  $ arr

--
Grzegorz