diff --git a/hw-rankselect.cabal b/hw-rankselect.cabal
--- a/hw-rankselect.cabal
+++ b/hw-rankselect.cabal
@@ -1,5 +1,5 @@
 name:                   hw-rankselect
-version:                0.0.0.6
+version:                0.1.0.0
 synopsis:               Conduits for tokenizing streams.
 description:            Please see README.md
 homepage:               http://github.com/haskell-works/hw-rankselect#readme
diff --git a/src/HaskellWorks/Data/Succinct/BalancedParens/Simple.hs b/src/HaskellWorks/Data/Succinct/BalancedParens/Simple.hs
--- a/src/HaskellWorks/Data/Succinct/BalancedParens/Simple.hs
+++ b/src/HaskellWorks/Data/Succinct/BalancedParens/Simple.hs
@@ -23,6 +23,7 @@
 import           HaskellWorks.Data.Succinct.RankSelect.Binary.Basic.Select0
 import           HaskellWorks.Data.Succinct.RankSelect.Binary.Basic.Select1
 import           HaskellWorks.Data.Succinct.RankSelect.Binary.Poppy512
+import           HaskellWorks.Data.Succinct.RankSelect.Binary.Poppy512S
 import           Prelude                                                    as P
 
 newtype SimpleBalancedParens a = SimpleBalancedParens a
@@ -134,6 +135,20 @@
   {-# INLINABLE parent      #-}
 
 instance BalancedParens (SimpleBalancedParens Poppy512) where
+  findOpen    v p = if v `openAt`  p then Just p else findOpen'  (Count 0) v (p - 1)
+  findClose   v p = if v `closeAt` p then Just p else findClose' (Count 0) v (p + 1)
+  enclose         = findOpen' (Count 1)
+  firstChild  v p = if openAt v p && openAt v (p + 1)   then Just (p + 1) else Nothing
+  nextSibling v p = if closeAt v p then Nothing else openAt v `mfilter` (findClose v p >>= (\q -> if p /= q then return (q + 1) else Nothing))
+  parent      v p = enclose   v p >>= (\r -> if r >= 1 then return r       else Nothing)
+  {-# INLINABLE findOpen    #-}
+  {-# INLINABLE findClose   #-}
+  {-# INLINABLE enclose     #-}
+  {-# INLINABLE firstChild  #-}
+  {-# INLINABLE nextSibling #-}
+  {-# INLINABLE parent      #-}
+
+instance BalancedParens (SimpleBalancedParens Poppy512S) where
   findOpen    v p = if v `openAt`  p then Just p else findOpen'  (Count 0) v (p - 1)
   findClose   v p = if v `closeAt` p then Just p else findClose' (Count 0) v (p + 1)
   enclose         = findOpen' (Count 1)
diff --git a/src/HaskellWorks/Data/Succinct/RankSelect/Binary/Poppy512S.hs b/src/HaskellWorks/Data/Succinct/RankSelect/Binary/Poppy512S.hs
--- a/src/HaskellWorks/Data/Succinct/RankSelect/Binary/Poppy512S.hs
+++ b/src/HaskellWorks/Data/Succinct/RankSelect/Binary/Poppy512S.hs
@@ -7,18 +7,21 @@
 
 import qualified Data.Vector.Storable                                       as DVS
 import           Data.Word
+import           HaskellWorks.Data.Bits.BitLength
 import           HaskellWorks.Data.Bits.BitRead
+import           HaskellWorks.Data.Bits.BitWise
 import           HaskellWorks.Data.Bits.PopCount.PopCount1
 import           HaskellWorks.Data.Positioning
 import           HaskellWorks.Data.Search
+import           HaskellWorks.Data.Succinct.RankSelect.Binary.Basic.Rank0
 import           HaskellWorks.Data.Succinct.RankSelect.Binary.Basic.Rank1
 import           HaskellWorks.Data.Succinct.RankSelect.Binary.Basic.Select1
 import           HaskellWorks.Data.Vector.VectorLike
 
 data Poppy512S = Poppy512S
-  { csPoppyBits     :: DVS.Vector Word64
-  , csPoppy512Index :: DVS.Vector Word64
-  , csPoppySamples  :: DVS.Vector Word64 -- Sampling position of each 8192 1-bit
+  { poppy512SBits     :: DVS.Vector Word64
+  , poppy512Index :: DVS.Vector Word64
+  , poppy512Samples  :: DVS.Vector Word64 -- Sampling position of each 8192 1-bit
   } deriving (Eq, Show)
 
 popCount1Range :: (DVS.Storable a, PopCount1 a) => Int -> Int -> DVS.Vector a -> Count
@@ -26,9 +29,9 @@
 
 makePoppy512S :: DVS.Vector Word64 -> Poppy512S
 makePoppy512S v = Poppy512S
-  { csPoppyBits     = v
-  , csPoppy512Index = DVS.constructN (((DVS.length v +           8 - 1) `div`           8) + 1) gen512Index
-  , csPoppySamples  = DVS.unfoldrN (fromIntegral (popCount1 v `div` 8192) + 1) genS (0, 0)
+  { poppy512SBits     = v
+  , poppy512Index = DVS.constructN (((DVS.length v +           8 - 1) `div`           8) + 1) gen512Index
+  , poppy512Samples  = DVS.unfoldrN (fromIntegral (popCount1 v `div` 8192) + 1) genS (0, 0)
   }
   where gen512Index u = let indexN = DVS.length u - 1 in
           if indexN == -1
@@ -43,12 +46,24 @@
                   else genS (pcz, n + 1)
           else Nothing
 
+instance BitLength Poppy512S where
+  bitLength v = vLength (poppy512SBits v) * bitLength (poppy512SBits v !!! 0)
+  {-# INLINABLE bitLength #-}
+
+instance TestBit Poppy512S where
+  (.?.) = (.?.) . poppy512SBits
+  {-# INLINE (.?.) #-}
+
 instance BitRead Poppy512S where
   bitRead = fmap makePoppy512S . bitRead
 
 instance Rank1 Poppy512S where
   rank1 (Poppy512S v i _) p =
-    Count (i !!! toPosition (p `div` 512)) + rank1 (DVS.drop (fromIntegral p `div` 512) v) (p `mod` 512)
+    Count (i !!! toPosition (p `div` 512)) + rank1 (DVS.drop ((fromIntegral p `div` 512) * 8) v) (p `mod` 512)
+
+instance Rank0 Poppy512S where
+  rank0 (Poppy512S v i _) p =
+    p `div` 512 * 512 - Count (i !!! toPosition (p `div` 512)) + rank0 (DVS.drop ((fromIntegral p `div` 512) * 8) v) (p `mod` 512)
 
 sampleRange :: Poppy512S -> Count -> (Word64, Word64)
 sampleRange (Poppy512S _ index samples) p =