#2 PackWords uses wrong divisor

I think intoWords / outOfWords should divide by 2⁶⁴ instead of 64.

 {-# INLINE intoWords #-}
 intoWords :: forall (n :: Nat) .
   (KnownNat n, 1 <= n) =>
   Finite n -> VU.Vector Word
 intoWords = evalState (VU.replicateM (wordLength @(Finite n)) go) . fromIntegral @_ @Natural
tural
   where go = do remaining <- get
-                let (d, r) = quotRem remaining bitsPerWord
+                let (d, r) = quotRem remaining (1 `shiftL` bitsPerWord)
                 put d >> pure (fromIntegral r)

 {-# INLINE outOfWords #-}
 outOfWords :: forall (n :: Nat) .
   (KnownNat n) =>
   VU.Vector Word -> Finite n
 outOfWords v = evalState (VU.foldM' go 0 v) 1
   where go old w = do power <- get
                       let placeValue = power * fromIntegral w
-                      modify (* bitsPerWord)
+                      modify (* fromInteger (1 `shiftL` bitsPerWord))
                       return (old + placeValue)

Yeah, I think you're right. Does the same issue apply to PackWords and PackBytes?

PackBytes looks alright to me.

Also, performance-wise it's better to shift by bitsPerWord rather than divide by 1 `shiftL` bitsPerWord.