newArray_ allocates an array full of garbage

In http://www.haskell.org/pipermail/haskell-cafe/2006-December/020115.html Stefan O'Rear points out that newArray_ allocates an array full of garbage. For ST this violates referential transparency, and it presumably also means we are leaking information we shouldn't.

For example, running

import Control.Monad.ST
import Data.Array.ST
import Data.Array
import System.Mem

tickle :: Int
tickle = runST (do {
     x <- newArray_ (0,100) ;
     (readArray :: STUArray s Int Int -> Int -> ST s Int) x 3
   })

main :: IO ()
main = do print $ length (replicate 100000 'a')
          performGC
          print tickle

produced

$ ./q
100000
46912506425344

Trac metadata

Trac field	Value
Version	6.6
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	libraries/base
Test case
Differential revisions
BlockedBy
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Blocking
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Operating system	Unknown
Architecture	Unknown