[remove update speculation as it can create blind updates
John Meacham <john@repetae.net>**20070602005802] hunk ./Grin/Optimize.hs 186
-        h (Update v (NodeC t xs)) | not (isMutableNodeTag t), t `member` sset = do
-            let t' = tagFlipFunction t
-            mtick $ "Optimize.speculate.update.{" ++ show t'
-            return (App t' xs [TyNode] :>>= [n1] :-> Update v n1)
+--        h (Update v (NodeC t xs)) | not (isMutableNodeTag t), t `member` sset = do
+--            let t' = tagFlipFunction t
+--            mtick $ "Optimize.speculate.update.{" ++ show t'
+--            return (App t' xs [TyNode] :>>= [n1] :-> Update v n1)