Fix docs and example

Author: Jaro Reinders

bench/Quicksort.hs

@@ -2,29 +2,15 @@
 module Quicksort (quicksort) where
 
 import Fleet.Array
-import Data.Tuple (Solo (..))
-
--- swap :: Int -> Int -> Array a -> Array a
--- swap !i !j !xs = set i (xs ! j) (set j (xs ! i) xs)
-
--- swap :: Int -> Int -> Array a -> Array a
--- swap !i !j !xs =
---   let
---     -- using this strict matching on MkSolo we
---     -- can ensure that the indexing happens
---     -- before the mutation (which would slow
---     -- down the indexing)
---     !(MkSolo x) = index i xs
---     !(MkSolo y) = index j xs
---   in set i y (set j x xs)
+import Data.Tuple (Solo (MkSolo))
 
 {-# INLINEABLE quicksort #-}
 quicksort :: Ord a => Int -> Int -> Array a -> Array a
 quicksort !l !r !xs
   | r - l <= 1 = xs
   | otherwise =
-    let !(MkSolo x) = index (r - 1) xs in
-    case partition l (r - 1) xs x of
+    let x@(MkSolo x') = index (r - 1) xs in
+    x `pseq` case partition l (r - 1) xs x' of
       (xs, m) -> quicksort l m (quicksort (m + 1) r (swap (r - 1) m xs))
 
 {-# INLINEABLE partition #-}

src/Fleet/Array.hs

@@ -121,9 +121,9 @@ toList (A v) = unsafeDupablePerformIO $ do
   --
   -- > swap !i !j !xs =
   -- >   let
-  -- >     x = index i xs
-  -- >     y = index j xs
-  -- >   in x `pseq` y `pseq` set i (getSolo y) (set j (getSolo x) xs)
+  -- >     x@(MkSolo x') = index i xs
+  -- >     y@(MkSolo y') = index j xs
+  -- >   in x `pseq` y `pseq` set i y' (set j x' xs)
   --
   -- In the future, we hope to write a GHC plugin that can automatically detect
   -- when pseq is necessary in common cases.