Merge pull request #130 from Shimuuar/uniq

Add uniq function

Author: dolio

Data/Vector.hs

@@ -113,7 +113,7 @@ module Data.Vector (
   -- * Working with predicates
 
   -- ** Filtering
-  filter, ifilter,
+  filter, ifilter, uniq,
   mapMaybe, imapMaybe,
   filterM,
   takeWhile, dropWhile,
@@ -1169,6 +1169,11 @@ ifilter :: (Int -> a -> Bool) -> Vector a -> Vector a
 {-# INLINE ifilter #-}
 ifilter = G.ifilter
 
+-- | /O(n)/ Drop repeated adjacent elements.
+uniq :: (Eq a) => Vector a -> Vector a
+{-# INLINE uniq #-}
+uniq = G.uniq
+
 -- | /O(n)/ Drop elements when predicate returns Nothing
 mapMaybe :: (a -> Maybe b) -> Vector a -> Vector b
 {-# INLINE mapMaybe #-}

Data/Vector/Fusion/Stream/Monadic.hs

@@ -40,7 +40,7 @@ module Data.Vector.Fusion.Stream.Monadic (
   eq, cmp,
 
   -- * Filtering
-  filter, filterM, mapMaybe, takeWhile, takeWhileM, dropWhile, dropWhileM,
+  filter, filterM, uniq, mapMaybe, takeWhile, takeWhileM, dropWhile, dropWhileM,
 
   -- * Searching
   elem, notElem, find, findM, findIndex, findIndexM,
@@ -719,6 +719,24 @@ filterM f (Stream step t) = Stream step' t
                   Skip    s' -> return $ Skip s'
                   Done       -> return $ Done
 
+-- | Drop repeated adjacent elements.
+uniq :: (Eq a, Monad m) => Stream m a -> Stream m a
+{-# INLINE_FUSED uniq #-}
+uniq (Stream step st) = Stream step' (Nothing,st)
+  where
+    {-# INLINE_INNER step' #-}
+    step' (Nothing, s) = do r <- step s
+                            case r of
+                              Yield x s' -> return $ Yield x (Just x , s')
+                              Skip  s'   -> return $ Skip  (Nothing, s')
+                              Done       -> return   Done
+    step' (Just x0, s) = do r <- step s
+                            case r of
+                              Yield x s' | x == x0   -> return $ Skip    (Just x0, s')
+                                         | otherwise -> return $ Yield x (Just x , s')
+                              Skip  s'   -> return $ Skip (Just x0, s')
+                              Done       -> return   Done
+
 -- | Longest prefix of elements that satisfy the predicate
 takeWhile :: Monad m => (a -> Bool) -> Stream m a -> Stream m a
 {-# INLINE takeWhile #-}

Data/Vector/Generic.hs

@@ -96,7 +96,7 @@ module Data.Vector.Generic (
   -- * Working with predicates
 
   -- ** Filtering
-  filter, ifilter,
+  filter, ifilter, uniq,
   mapMaybe, imapMaybe,
   filterM,
   takeWhile, dropWhile,
@@ -1315,6 +1315,11 @@ ifilter f = unstream
           . inplace (S.map snd . S.filter (uncurry f) . S.indexed) toMax
           . stream
 
+-- | /O(n)/ Drop repeated adjacent elements.
+uniq :: (Vector v a, Eq a) => v a -> v a
+{-# INLINE uniq #-}
+uniq = unstream . inplace S.uniq toMax . stream
+
 -- | /O(n)/ Drop elements when predicate returns Nothing
 mapMaybe :: (Vector v a, Vector v b) => (a -> Maybe b) -> v a -> v b
 {-# INLINE mapMaybe #-}

Data/Vector/Primitive.hs

@@ -92,7 +92,7 @@ module Data.Vector.Primitive (
   -- * Working with predicates
 
   -- ** Filtering
-  filter, ifilter,
+  filter, ifilter, uniq,
   mapMaybe, imapMaybe,
   filterM,
   takeWhile, dropWhile,
@@ -928,6 +928,11 @@ ifilter :: Prim a => (Int -> a -> Bool) -> Vector a -> Vector a
 {-# INLINE ifilter #-}
 ifilter = G.ifilter
 
+-- | /O(n)/ Drop repeated adjacent elements.
+uniq :: (Prim a, Eq a) => Vector a -> Vector a
+{-# INLINE uniq #-}
+uniq = G.uniq
+
 -- | /O(n)/ Drop elements when predicate returns Nothing
 mapMaybe :: (Prim a, Prim b) => (a -> Maybe b) -> Vector a -> Vector b
 {-# INLINE mapMaybe #-}

Data/Vector/Storable.hs

@@ -89,7 +89,7 @@ module Data.Vector.Storable (
   -- * Working with predicates
 
   -- ** Filtering
-  filter, ifilter,
+  filter, ifilter, uniq,
   mapMaybe, imapMaybe,
   filterM,
   takeWhile, dropWhile,
@@ -938,6 +938,11 @@ ifilter :: Storable a => (Int -> a -> Bool) -> Vector a -> Vector a
 {-# INLINE ifilter #-}
 ifilter = G.ifilter
 
+-- | /O(n)/ Drop repeated adjacent elements.
+uniq :: (Storable a, Eq a) => Vector a -> Vector a
+{-# INLINE uniq #-}
+uniq = G.uniq
+
 -- | /O(n)/ Drop elements when predicate returns Nothing
 mapMaybe :: (Storable a, Storable b) => (a -> Maybe b) -> Vector a -> Vector b
 {-# INLINE mapMaybe #-}

Data/Vector/Unboxed.hs

@@ -119,7 +119,7 @@ module Data.Vector.Unboxed (
   -- * Working with predicates
 
   -- ** Filtering
-  filter, ifilter,
+  filter, ifilter, uniq,
   mapMaybe, imapMaybe,
   filterM,
   takeWhile, dropWhile,
@@ -979,6 +979,11 @@ filter :: Unbox a => (a -> Bool) -> Vector a -> Vector a
 {-# INLINE filter #-}
 filter = G.filter
 
+-- | /O(n)/ Drop repeated adjacent elements.
+uniq :: (Unbox a, Eq a) => Vector a -> Vector a
+{-# INLINE uniq #-}
+uniq = G.uniq
+
 -- | /O(n)/ Drop elements that do not satisfy the predicate which is applied to
 -- values and their indices
 ifilter :: Unbox a => (Int -> a -> Bool) -> Vector a -> Vector a

tests/Tests/Vector.hs

@@ -172,6 +172,7 @@ testPolymorphicFunctions _ = $(testProperties [
 
         -- Filtering
         'prop_filter, 'prop_ifilter, {- prop_filterM, -}
+        'prop_uniq,
         'prop_mapMaybe, 'prop_imapMaybe,
         'prop_takeWhile, 'prop_dropWhile,
 
@@ -410,6 +411,8 @@ testPolymorphicFunctions _ = $(testProperties [
       where
         prop :: P ((a -> v a) -> v a -> v a) = V.concatMap `eq` concatMap
 
+    prop_uniq :: P (v a -> v a)
+      = V.uniq `eq` (map head . group)
     --prop_span         = (V.span :: (a -> Bool) -> v a -> (v a, v a))  `eq2` span
     --prop_break        = (V.break :: (a -> Bool) -> v a -> (v a, v a)) `eq2` break
     --prop_splitAt      = (V.splitAt :: Int -> v a -> (v a, v a))       `eq2` splitAt