Add rToMixed and stoMixed

These are somewhat redundant because one can just open up the Ranked and
Shaped newtype constructors, but let's complete the triangle of
conversion functions.

3 files changed, 10 insertions, 2 deletions

diff --git a/src/Data/Array/Nested.hs b/src/Data/Array/Nested.hs
index 7eb7b18..e4bd517 100644
--- a/src/Data/Array/Nested.hs
+++ b/src/Data/Array/Nested.hs
@@ -18,7 +18,7 @@ module Data.Array.Nested (
   rlift, rlift2,
   -- ** Conversions
   rtoXArrayPrim, rfromXArrayPrim,
-  rcastToShaped,
+  rcastToShaped, rtoMixed,
   rfromOrthotope, rtoOrthotope,
 
   -- * Shaped arrays
@@ -39,7 +39,7 @@ module Data.Array.Nested (
   slift, slift2,
   -- ** Conversions
   stoXArrayPrim, sfromXArrayPrim,
-  stoRanked,
+  stoRanked, stoMixed,
   sfromOrthotope, stoOrthotope,
 
   -- * Mixed arrays
@@ -78,6 +78,8 @@ module Data.Array.Nested (
   KnownPerm(..),
   NumElt, FloatElt,
   Rank,
+  Replicate,
+  MapJust,
 ) where
 
 import Prelude hiding (mappend, mconcat)
diff --git a/src/Data/Array/Nested/Internal/Ranked.hs b/src/Data/Array/Nested/Internal/Ranked.hs
index 735d1a3..ffa1cea 100644
--- a/src/Data/Array/Nested/Internal/Ranked.hs
+++ b/src/Data/Array/Nested/Internal/Ranked.hs
@@ -524,3 +524,6 @@ mtoRanked arr
     convSh (smn :$% (sh :: IShX sh'T))
       | Refl <- lemReplicateSucc @(Nothing @Nat) @(Rank sh'T)
       = SUnknown (fromSMayNat' smn) :$% convSh sh
+
+rtoMixed :: forall n a. Elt a => Ranked n a -> Mixed (Replicate n Nothing) a
+rtoMixed (Ranked arr) = arr
diff --git a/src/Data/Array/Nested/Internal/Shaped.hs b/src/Data/Array/Nested/Internal/Shaped.hs
index 995507f..023f96c 100644
--- a/src/Data/Array/Nested/Internal/Shaped.hs
+++ b/src/Data/Array/Nested/Internal/Shaped.hs
@@ -459,3 +459,6 @@ mcastToShaped arr targetsh
   , Refl <- lemAppNil @(MapJust sh')
   , Refl <- lemRankMapJust targetsh
   = Shaped (mcast (ssxFromShape (mshape arr)) (shCvtSX targetsh) (Proxy @'[]) arr)
+
+stoMixed :: forall sh a. Shaped sh a -> Mixed (MapJust sh) a
+stoMixed (Shaped arr) = arr