diff --git a/library/PrimitiveExtras/PrimArray.hs b/library/PrimitiveExtras/PrimArray.hs
--- a/library/PrimitiveExtras/PrimArray.hs
+++ b/library/PrimitiveExtras/PrimArray.hs
@@ -6,6 +6,7 @@
 import qualified Data.Serialize as Cereal
 import qualified Data.Vector.Unboxed as UnboxedVector
 import qualified Data.Vector.Primitive as PrimitiveVector
+import qualified PrimitiveExtras.Folds as Folds
 
 
 oneHot :: Prim a => Int {-^ Size -} -> Int {-^ Index -} -> a -> PrimArray a
@@ -99,3 +100,10 @@
   where
     size = int (sizeofPrimArray primArrayValue)
     elements = traverse_ element primArrayValue
+
+{-|
+Given a size of the array,
+construct a fold, which produces an array of index counts.
+-}
+indexCountsFold :: (Integral count, Prim count) => Int {-^ Array size -} -> Fold Int (PrimArray count)
+indexCountsFold = Folds.indexCounts
diff --git a/primitive-extras.cabal b/primitive-extras.cabal
--- a/primitive-extras.cabal
+++ b/primitive-extras.cabal
@@ -1,7 +1,7 @@
 name:
   primitive-extras
 version:
-  0.6
+  0.6.1
 category:
   Primitive
 synopsis: