diff --git a/Rebuild.hs b/Rebuild.hs
@@ -15,6 +15,7 @@ import Data.STRef
import Data.String
import Data.Word
+import Control.DeepSeq
import Data.Vector.Unboxed (Vector)
import qualified Data.Vector.Unboxed as Vector (create, length)
import qualified Data.Vector.Unboxed.Mutable as Vector hiding (length)
@@ -46,8 +47,8 @@ rebuildAsVector bytes = byteVector
n <- readSTRef counter
return (Vector.unsafeSlice 0 n v)
writeOneByte v counter b = do n <- readSTRef counter
- Vector.unsafeWrite v n b
+ w v n b
modifySTRef counter (+!1)
+ (+!) a b = ((+) $!! a) $!! b
+ w v n b = (Vector.unsafeWrite v $!! n) $!! b
+! doesn't work unless modifySTRef is already strict in the result of the function application. You need to write modifySTRef' that seq:s the result of the function application before calling writeSTRef.
Just double checked. modifySTRef is too lazy:
-- |Mutate the contents of an 'STRef'
modifySTRef :: STRef s a -> (a -> a) -> ST s ()
modifySTRef ref f = writeSTRef ref . f =<< readSTRef ref
We need Data.STRef.Strict