diff --git a/Data/PrimitiveArray.hs b/Data/PrimitiveArray.hs
--- a/Data/PrimitiveArray.hs
+++ b/Data/PrimitiveArray.hs
@@ -43,7 +43,7 @@
   fromListM :: PrimMonad m => sh -> sh -> [elm] -> m (marr (PrimState m) sh elm)
 
   -- | Creates a new array with the given bounds with each element within the
-  -- array being in a random state.
+  -- array being in an undefined state.
 
   newM :: PrimMonad m => sh -> sh -> m (marr (PrimState m) sh elm)
 
@@ -96,8 +96,6 @@
 {-# INLINE (!) #-}
 
 -- | Returns true if the index is valid for the array.
---
--- TODO can't give a typedef
 
 inBoundsM :: MPrimArrayOps marr sh elm => marr s sh elm -> sh -> Bool
 inBoundsM marr idx = let (lb,ub) = boundsM marr in inShapeRange lb ub idx
diff --git a/Data/PrimitiveArray/Zero.hs b/Data/PrimitiveArray/Zero.hs
new file mode 100644
--- /dev/null
+++ b/Data/PrimitiveArray/Zero.hs
@@ -0,0 +1,71 @@
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE TypeFamilies #-}
+
+-- | Boxed, primitive arrays. A good use-case is to store boxed or unboxed
+-- vectors.
+
+module Data.PrimitiveArray.Zero where
+
+import Control.Monad
+import Data.Array.Repa.Index
+import Data.Array.Repa.Shape
+import Data.Primitive
+import Data.Primitive.Array
+import Data.Primitive.Types
+import Control.Exception (assert)
+
+import Data.ExtShape
+import Data.PrimitiveArray
+
+
+
+-- | Monadic arrays of primitive type.
+
+data MArr0 s sh elm = MArr0 !sh {-# UNPACK #-} !(MutableArray s elm)
+
+-- | Immutable arrays of primitive type.
+
+data Arr0 sh elm = Arr0 !sh {-# UNPACK #-} !(Array elm)
+
+
+
+type instance MutArray Arr0 = MArr0
+
+-- NOTE inLb, inUb is including bound, while exUb is excluding upper bound.
+-- Differentiates between largest included index, first excluded index.
+
+instance (Shape sh, ExtShape sh, Prim elm) => MPrimArrayOps MArr0 sh elm where
+  boundsM (MArr0 exUb _) = (zeroDim,exUb `subDim` unitDim)
+  fromListM inLb inUb xs = do
+    ma <- newM inLb inUb
+    let exUb = inUb `addDim` unitDim
+    let (MArr0 _ mba) = ma
+    zipWithM_ (\k x -> assert (length xs == size exUb) $ writeArray mba k x) [0.. toIndex exUb inUb] xs
+    return ma
+  newM inLb inUb = let exUb = inUb `addDim` unitDim in
+    unless (inLb == zeroDim) (error "MArr0 lb/=zeroDim") >>
+    MArr0 exUb `liftM` newArray (size exUb) undefined
+  newWithM inLb inUb def = do
+    let exUb = inUb `addDim` unitDim
+    ma <- newM inLb inUb
+    let (MArr0 _ mba) = ma
+    forM_ [0 .. toIndex exUb inUb] $ \k -> writeArray mba k def
+    return ma
+  readM (MArr0 exUb mba) idx = assert (inShape exUb idx) $ readArray mba (toIndex exUb idx)
+  writeM (MArr0 exUb mba) idx elm = assert (inShape exUb idx) $ writeArray mba (toIndex exUb idx) elm
+  {-# INLINE boundsM #-}
+  {-# INLINE fromListM #-}
+  {-# INLINE newM #-}
+  {-# INLINE newWithM #-}
+  {-# INLINE readM #-}
+  {-# INLINE writeM #-}
+
+instance (Shape sh, ExtShape sh, Prim elm) => PrimArrayOps Arr0 sh elm where
+  bounds (Arr0 exUb _) = (zeroDim,exUb `subDim` unitDim)
+  freeze (MArr0 exUb mba) = Arr0 exUb `liftM` unsafeFreezeArray mba
+  index (Arr0 exUb ba) idx = assert (inShape exUb idx) $ indexArray ba (toIndex exUb idx)
+  {-# INLINE bounds #-}
+  {-# INLINE freeze #-}
+  {-# INLINE index #-}
+
diff --git a/PrimitiveArray.cabal b/PrimitiveArray.cabal
--- a/PrimitiveArray.cabal
+++ b/PrimitiveArray.cabal
@@ -1,5 +1,5 @@
 Name:           PrimitiveArray
-Version:        0.2.0.0
+Version:        0.2.1.0
 License:        BSD3
 License-file:   LICENSE
 Author:         Christian Hoener zu Siederdissen
@@ -33,6 +33,7 @@
     Data.ExtShape
     Data.PrimitiveArray
     Data.PrimitiveArray.Unboxed.Zero
+    Data.PrimitiveArray.Zero
   Build-depends:
     base >= 4 && <5,
     primitive >= 0.4,