Make fromListN functions good consumers

...in terms of list fusion.

Data/Primitive/Array.hs

@@ -587,17 +587,18 @@ mapArray' f a =
 -- | Create an array from a list of a known length. If the length
 -- of the list does not match the given length, this throws an exception.
 arrayFromListN :: Int -> [a] -> Array a
+{-# INLINE arrayFromListN #-} -- Inline for list fusion
 arrayFromListN n l =
   createArray n (die "fromListN" "uninitialized element") $ \sma ->
-    let go !ix [] = if ix == n
+    let z !ix = if ix == n
           then return ()
           else die "fromListN" "list length less than specified size"
-        go !ix (x : xs) = if ix < n
+        f x k = GHC.Exts.oneShot $ \ !ix -> if ix < n
           then do
             writeArray sma ix x
-            go (ix+1) xs
+            k (ix+1)
           else die "fromListN" "list length greater than specified size"
-    in go 0 l
+    in foldr f z l 0
 
 -- | Create an array from a list.
 arrayFromList :: [a] -> Array a

Data/Primitive/ByteArray.hs

@@ -379,16 +379,17 @@ byteArrayFromList xs = byteArrayFromListN (length xs) xs
 -- | Create a 'ByteArray' from a list of a known length. If the length
 -- of the list does not match the given length, this throws an exception.
 byteArrayFromListN :: forall a. Prim a => Int -> [a] -> ByteArray
+{-# INLINE byteArrayFromListN #-} -- Inline for list fusion
 byteArrayFromListN n ys = createByteArray (n * sizeOfType @a) $ \marr ->
-  let go !ix [] = if ix == n
+  let z !ix = if ix == n
         then return ()
         else die "byteArrayFromListN" "list length less than specified size"
-      go !ix (x : xs) = if ix < n
+      f x k = GHC.Exts.oneShot $ \ !ix -> if ix < n
         then do
           writeByteArray marr ix x
-          go (ix + 1) xs
+          k (ix + 1)
         else die "byteArrayFromListN" "list length greater than specified size"
-  in go 0 ys
+  in foldr f z ys 0
 
 unI# :: Int -> Int#
 unI# (I# n#) = n#

Data/Primitive/PrimArray.hs

@@ -235,16 +235,17 @@ primArrayFromList vs = primArrayFromListN (L.length vs) vs
 -- | Create a 'PrimArray' from a list of a known length. If the length
 -- of the list does not match the given length, this throws an exception.
 primArrayFromListN :: forall a. Prim a => Int -> [a] -> PrimArray a
+{-# INLINE primArrayFromListN #-} -- Inline for list fusion
 primArrayFromListN len vs = createPrimArray len $ \arr ->
-  let go [] !ix = if ix == len
+  let z !ix = if ix == len
         then return ()
         else die "fromListN" "list length less than specified size"
-      go (a : as) !ix = if ix < len
+      f a k = GHC.Exts.oneShot $ \ !ix -> if ix < len
         then do
           writePrimArray arr ix a
-          go as (ix + 1)
+          k (ix + 1)
         else die "fromListN" "list length greater than specified size"
-  in go vs 0
+  in foldr f z vs 0
 
 -- | Convert a 'PrimArray' to a list.
 {-# INLINE primArrayToList #-}

Data/Primitive/SmallArray.hs

@@ -924,18 +924,19 @@ instance (Typeable s, Typeable a) => Data (SmallMutableArray s a) where
 -- | Create a 'SmallArray' from a list of a known length. If the length
 -- of the list does not match the given length, this throws an exception.
 smallArrayFromListN :: Int -> [a] -> SmallArray a
+{-# INLINE smallArrayFromListN #-} -- Inline for list fusion
 smallArrayFromListN n l =
   createSmallArray n
       (die "smallArrayFromListN" "uninitialized element") $ \sma ->
-  let go !ix [] = if ix == n
+  let z !ix = if ix == n
         then return ()
         else die "smallArrayFromListN" "list length less than specified size"
-      go !ix (x : xs) = if ix < n
+      f x k = GHC.Exts.oneShot $ \ !ix -> if ix < n
         then do
           writeSmallArray sma ix x
-          go (ix + 1) xs
+          k (ix + 1)
         else die "smallArrayFromListN" "list length greater than specified size"
-  in go 0 l
+  in foldr f z l 0
 
 -- | Create a 'SmallArray' from a list.
 smallArrayFromList :: [a] -> SmallArray a