Improve scastToMixed's implementation

1 files changed, 5 insertions, 5 deletions

diff --git a/src/Data/Array/Nested/Internal/Shaped.hs b/src/Data/Array/Nested/Internal/Shaped.hs
index 76e0e6d..2a8c206 100644
--- a/src/Data/Array/Nested/Internal/Shaped.hs
+++ b/src/Data/Array/Nested/Internal/Shaped.hs
@@ -488,8 +488,8 @@ stoMixed (Shaped arr) = arr
 -- compatibility check.
 scastToMixed :: forall sh sh' a. (Elt a, Rank sh ~ Rank sh')
              => IShX sh' -> Shaped sh a -> Mixed sh' a
-scastToMixed shx (Shaped arr)
-  | Refl <- lemAppNil @sh'
-  , Refl <- lemAppNil @(MapJust sh)
-  , Refl <- lemRankMapJust (shCvtXS' @sh (mshape arr))
-  = mcast (ssxFromShape (mshape arr)) shx (Proxy @'[]) arr
+scastToMixed shx (Shaped arr) =
+  case shxEqual shx (mshape arr) of
+    Just Refl -> arr
+    Nothing -> error $ "scastToMixed: Given shape (" ++ show shx ++ ") is not equal to " ++
+                       "the shape of the array (" ++ show (mshape arr) ++ ")"