1 files changed, 31 insertions, 15 deletions
diff --git a/src/Data/Array/Nested/Ranked/Shape.hs b/src/Data/Array/Nested/Ranked/Shape.hs
index ea22a2b..9815c42 100644
--- a/src/Data/Array/Nested/Ranked/Shape.hs
+++ b/src/Data/Array/Nested/Ranked/Shape.hs
@@ -33,7 +33,6 @@ import Control.DeepSeq (NFData(..))
 import Data.Coerce (coerce)
 import Data.Foldable qualified as Foldable
 import Data.Kind (Type)
-import Data.List (genericLength)
 import Data.Proxy
 import Data.Type.Equality
 import GHC.Exts (Int(..), Int#, quotRemInt#)
@@ -81,9 +80,7 @@ instance Foldable (ListR n) where
   {-# INLINE foldr #-}
   foldr _ z ZR = z
   foldr f z (x ::: xs) = f x (foldr f z xs)
-  {-# INLINEABLE toList #-}
-  toList ZR = []
-  toList (i ::: is) = i : Foldable.toList is
+  toList = listrToList
   null ZR = False
   null _ = True
 
@@ -137,6 +134,11 @@ listrFromList n l = error $ "listrFromList: Mismatched list length (type says "
                             ++ show (fromSNat n) ++ ", list has length "
                             ++ show (length l) ++ ")"
 
+{-# INLINEABLE listrToList #-}
+listrToList :: ListR n i -> [i]
+listrToList ZR = []
+listrToList (i ::: is) = i : listrToList is
+
 listrHead :: ListR (n + 1) i -> i
 listrHead (i ::: _) = i
 
@@ -174,16 +176,16 @@ listrZipWith _ _ _ =
   error "listrZipWith: impossible pattern needlessly required"
 
 listrPermutePrefix :: forall i n. [Int] -> ListR n i -> ListR n i
-listrPermutePrefix = \perm sh -> withSomeSNat (genericLength perm) $ \case
-  Just permlen@SNat->
-    let sperm = listrFromList permlen perm
-    in case listrRank sh of
-      shlen@SNat -> case cmpNat permlen shlen of
-        LTI -> let (pre, post) = listrSplitAt permlen sh in listrAppend (applyPermRFull permlen sperm pre) post
-        EQI -> let (pre, post) = listrSplitAt permlen sh in listrAppend (applyPermRFull permlen sperm pre) post
-        GTI -> error $ "Length of permutation (" ++ show (fromSNat' permlen) ++ ")"
-                       ++ " > length of shape (" ++ show (fromSNat' shlen) ++ ")"
-  Nothing -> error "listrPermutePrefix: impossible negative list length"
+listrPermutePrefix = \perm sh ->
+  TN.withSomeSNat (fromIntegral (length perm)) $ \permlen@SNat ->
+  case listrRank sh of { shlen@SNat ->
+  let sperm = listrFromList permlen perm in
+  case cmpNat permlen shlen of
+    LTI -> let (pre, post) = listrSplitAt permlen sh in listrAppend (applyPermRFull permlen sperm pre) post
+    EQI -> let (pre, post) = listrSplitAt permlen sh in listrAppend (applyPermRFull permlen sperm pre) post
+    GTI -> error $ "Length of permutation (" ++ show (fromSNat' permlen) ++ ")"
+                   ++ " > length of shape (" ++ show (fromSNat' shlen) ++ ")"
+  }
   where
     listrSplitAt :: m <= n' => SNat m -> ListR n' i -> (ListR m i, ListR (n' - m) i)
     listrSplitAt SZ sh = (ZR, sh)
@@ -245,6 +247,13 @@ ixrZero :: SNat n -> IIxR n
 ixrZero SZ = ZIR
 ixrZero (SS n) = 0 :.: ixrZero n
 
+ixrFromList :: forall n i. SNat n -> [i] -> IxR n i
+ixrFromList = coerce (listrFromList @_ @i)
+
+{-# INLINEABLE ixrToList #-}
+ixrToList :: forall n i. IxR n i -> [i]
+ixrToList = coerce (listrToList @_ @i)
+
 ixrHead :: IxR (n + 1) i -> i
 ixrHead (IxR list) = listrHead list
 
@@ -330,6 +339,13 @@ shrSize :: IShR n -> Int
 shrSize ZSR = 1
 shrSize (n :$: sh) = n * shrSize sh
 
+shrFromList :: forall n i. SNat n -> [i] -> ShR n i
+shrFromList = coerce (listrFromList @_ @i)
+
+{-# INLINEABLE shrToList #-}
+shrToList :: forall n i. ShR n i -> [i]
+shrToList = coerce (listrToList @_ @i)
+
 shrHead :: ShR (n + 1) i -> i
 shrHead (ShR list) = listrHead list
 
@@ -366,7 +382,7 @@ shrEnum = shrEnum'
 shrEnum' :: Num i => IShR sh -> [IxR sh i]
 shrEnum' sh = [fromLin sh suffixes li# | I# li# <- [0 .. shrSize sh - 1]]
   where
-    suffixes = drop 1 (scanr (*) 1 (Foldable.toList sh))
+    suffixes = drop 1 (scanr (*) 1 (shrToList sh))
 
     fromLin :: Num i => IShR sh -> [Int] -> Int# -> IxR sh i
     fromLin ZSR _ _ = ZIR