4 files changed, 40 insertions, 0 deletions
diff --git a/src/Data/Array/Nested/Mixed.hs b/src/Data/Array/Nested/Mixed.hs
index 144230e..4028b1d 100644
--- a/src/Data/Array/Nested/Mixed.hs
+++ b/src/Data/Array/Nested/Mixed.hs
@@ -5,6 +5,7 @@
 {-# LANGUAGE DerivingVia #-}
 {-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE GADTs #-}
 {-# LANGUAGE ImportQualifiedPost #-}
 {-# LANGUAGE InstanceSigs #-}
 {-# LANGUAGE RankNTypes #-}
@@ -287,6 +288,8 @@ mremArray = mliftNumElt2 (liftO2 . intEltRem)
 matan2Array :: (FloatElt a, PrimElt a) => Mixed sh a -> Mixed sh a -> Mixed sh a
 matan2Array = mliftNumElt2 (liftO2 . floatEltAtan2)
 
+type MRepTrans = RepTrans (SMayNat Int SNat)
+
 -- | Allowable element types in a mixed array, and by extension in a 'Ranked' or
 -- 'Shaped' array. Note the polymorphic instance for 'Elt' of @'Primitive'
 -- a@; see the documentation for 'Primitive' for more details.
@@ -340,6 +343,8 @@ class Elt a where
   mtranspose :: forall is sh. (IsPermutation is, Rank is <= Rank sh)
              => Perm is -> Mixed sh a -> Mixed (PermutePrefix is sh) a
 
+  mreptransPartial :: Proxy sh' -> MRepTrans sh1 sh2 -> Mixed (sh1 ++ sh') a -> Mixed (sh2 ++ sh') a
+
   -- | All arrays in the input must have equal shapes, including subarrays
   -- inside their elements.
   mconcat :: NonEmpty (Mixed (Nothing : sh) a) -> Mixed (Nothing : sh) a
@@ -445,6 +450,8 @@ instance Storable a => Elt (Primitive a) where
     M_Primitive (shxPermutePrefix perm sh)
                 (X.transpose (ssxFromShX sh) perm arr)
 
+  mreptransPartial p descr (M_Primitive sh arr) = _
+
   mconcat :: forall sh. NonEmpty (Mixed (Nothing : sh) (Primitive a)) -> Mixed (Nothing : sh) (Primitive a)
   mconcat l@(M_Primitive (_ :$% sh) _ :| _) =
     let result = X.concat (ssxFromShX sh) (fmap (\(M_Primitive _ arr) -> arr) l)
diff --git a/src/Data/Array/Nested/Permutation.hs b/src/Data/Array/Nested/Permutation.hs
index 03d1640..c893dac 100644
--- a/src/Data/Array/Nested/Permutation.hs
+++ b/src/Data/Array/Nested/Permutation.hs
@@ -281,3 +281,12 @@ lemRankDropLen ZKX (_ `PCons` _) = error "1 <= 0"
 lemIndexSucc :: Proxy i -> Proxy a -> Proxy l
              -> Index (i + 1) (a : l) :~: Index i l
 lemIndexSucc _ _ _ = unsafeCoerceRefl
+
+
+-- * Replication-transpositions
+
+data RepTrans f sh sh' where
+  RTNil :: RepTrans f sh '[]
+  RTUse :: SNat i -> RepTrans f sh sh' -> RepTrans f sh (Index i sh : sh')
+  RTRep :: f n -> RepTrans f sh sh' -> RepTrans f sh (n : sh')
+
diff --git a/src/Data/Array/Nested/Shaped.hs b/src/Data/Array/Nested/Shaped.hs
index 198a068..2c64bb4 100644
--- a/src/Data/Array/Nested/Shaped.hs
+++ b/src/Data/Array/Nested/Shaped.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE DataKinds #-}
+{-# LANGUAGE GADTs #-}
 {-# LANGUAGE ImportQualifiedPost #-}
 {-# LANGUAGE RankNTypes #-}
 {-# LANGUAGE ScopedTypeVariables #-}
@@ -199,6 +200,14 @@ srerank :: forall sh1 sh2 sh a b. (PrimElt a, PrimElt b)
 srerank sh sh2 f (stoPrimitive -> arr) =
   sfromPrimitive $ srerankP sh sh2 (stoPrimitive . f . sfromPrimitive) arr
 
+-- data RepTrans sh sh' where
+--   RTNil :: RepTrans sh '[]
+--   RTUse :: SNat i -> RepTrans sh sh' -> RepTrans sh (Index i sh : sh')
+--   RTRep :: SNat n -> RepTrans sh sh' -> RepTrans sh (n : sh')
+
+-- sreptrans :: RepTrans sh sh' -> Shaped sh a -> Shaped sh' a
+-- sreptrans 
+
 sreplicate :: forall sh sh' a. Elt a => ShS sh -> Shaped sh' a -> Shaped (sh ++ sh') a
 sreplicate sh (Shaped arr)
   | Refl <- lemMapJustApp sh (Proxy @sh')
diff --git a/src/Data/Array/XArray.hs b/src/Data/Array/XArray.hs
index bf47622..f10e4f0 100644
--- a/src/Data/Array/XArray.hs
+++ b/src/Data/Array/XArray.hs
@@ -4,6 +4,7 @@
 {-# LANGUAGE GADTs #-}
 {-# LANGUAGE ImportQualifiedPost #-}
 {-# LANGUAGE NoStarIsType #-}
+{-# LANGUAGE RankNTypes #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE StandaloneKindSignatures #-}
 {-# LANGUAGE StrictData #-}
@@ -245,6 +246,20 @@ transpose2 ssh1 ssh2 (XArray arr)
   , let n1 = ssxLength ssh1
   = XArray (S.transpose (ssxIotaFrom ssh2 n1 ++ ssxIotaFrom ssh1 0) arr)
 
+reptransPartial :: forall f sh sh' a. (forall n. f n -> Int) -> RepTrans f sh sh' -> XArray sh a -> XArray sh' a
+reptransPartial unNat = \descr (XArray (ORS.A (ORG.A sh (OI.T strides off vec)))) ->
+  XArray (ORS.A (ORG.A (computeShape descr sh) (OI.T (computeStrides descr strides) off vec)))
+  where
+    computeShape :: RepTrans f sh1 sh2 -> S.ShapeL -> S.ShapeL
+    computeShape RTNil _ = []
+    computeShape (RTUse idx descr) sh = sh !! fromSNat' idx : computeShape descr sh
+    computeShape (RTRep n descr) sh = unNat n : computeShape descr sh
+
+    computeStrides :: RepTrans f sh1 sh2 -> [Int] -> [Int]
+    computeStrides RTNil _ = []
+    computeStrides (RTUse idx descr) str = str !! fromSNat' idx : computeStrides descr str
+    computeStrides (RTRep _ descr) str = 0 : computeStrides descr str
+
 sumFull :: (Storable a, NumElt a) => StaticShX sh -> XArray sh a -> a
 sumFull _ (XArray arr) =
   S.unScalar $