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{-# LANGUAGE UnboxedTuples, MagicHash, BlockArguments #-}
import GHC.Exts
import GHC.Types
doSomething :: Word -> IO Word
doSomething (W# x) = IO \s ->
case newByteArray# 7096# s of -- we need a large ByteArray#
(# s, mba #) -> case shrinkMutableByteArray# mba 7020# s of -- shrunk
s -> case unsafeFreezeByteArray# mba s of
(# s, ba #) -> (# s, W# (indexWordArray# ba 18#) #)
main :: IO ()
main = do
xs <- mapM doSomething [0..300000] -- we need enough elements (to trigger a GC maybe?)
print (length xs)
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