1 files changed, 6 insertions, 7 deletions
diff --git a/System/Random/Shuffle.hs b/System/Random/Shuffle.hs
index 774e7b4..d3cd387 100644
--- a/System/Random/Shuffle.hs
+++ b/System/Random/Shuffle.hs
@@ -25,8 +25,7 @@ module System.Random.Shuffle
 where
 
 import Control.Monad
-  ( liftM,
-    liftM2,
+  ( liftM2,
   )
 import Control.Monad.Random
   ( MonadRandom,
@@ -49,13 +48,13 @@ data Tree a
 
 -- | Convert a sequence (e1...en) to a complete binary tree
 buildTree :: [a] -> Tree a
-buildTree = (fix growLevel) . (map Leaf)
+buildTree = fix growLevel . map Leaf
   where
     growLevel _ [node] = node
     growLevel self l = self $ inner l
     inner [] = []
     inner [e] = [e]
-    inner (e1 : e2 : es) = e1 `seq` e2 `seq` (join e1 e2) : inner es
+    inner (e1 : e2 : es) = e1 `seq` e2 `seq` join e1 e2 : inner es
     join l@(Leaf _) r@(Leaf _) = Node 2 l r
     join l@(Node ct _ _) r@(Leaf _) = Node (ct + 1) l r
     join l@(Leaf _) r@(Node ct _ _) = Node (ct + 1) l r
@@ -70,7 +69,7 @@ shuffle elements = shuffleTree (buildTree elements)
   where
     shuffleTree (Leaf e) [] = [e]
     shuffleTree tree (r : rs) =
-      let (b, rest) = extractTree r tree in b : (shuffleTree rest rs)
+      let (b, rest) = extractTree r tree in b : shuffleTree rest rs
     shuffleTree _ _ = error "[shuffle] called with lists of different lengths"
     -- Extracts the n-th element from the tree and returns
     -- that element, paired with a tree with the element
@@ -99,7 +98,7 @@ shuffle' elements len = shuffle elements . rseq len
     -- independent sample from a uniform random distribution
     -- [0..n-i]
     rseq :: RandomGen gen => Int -> gen -> [Int]
-    rseq n = fst . unzip . rseq' (n - 1)
+    rseq n = map fst . rseq' (n - 1)
       where
         rseq' :: RandomGen gen => Int -> gen -> [(Int, gen)]
         rseq' 0 _ = []
@@ -111,7 +110,7 @@ shuffle' elements len = shuffle elements . rseq len
 shuffleM :: (MonadRandom m) => [a] -> m [a]
 shuffleM elements
   | null elements = return []
-  | otherwise = liftM (shuffle elements) (rseqM (length elements - 1))
+  | otherwise = shuffle elements <$> rseqM (length elements - 1)
   where
     rseqM :: (MonadRandom m) => Int -> m [Int]
     rseqM 0 = return []