diff --git a/core/src/Streamly/FileSystem/Path.hs b/core/src/Streamly/FileSystem/Path.hs
index 166ecf5923..b2e4079862 100644
--- a/core/src/Streamly/FileSystem/Path.hs
+++ b/core/src/Streamly/FileSystem/Path.hs
@@ -125,7 +125,7 @@ module Streamly.FileSystem.Path
     , isBranch
 
     -- * Combinators
-    , append
+    , extend
     )
 where
 
diff --git a/core/src/Streamly/FileSystem/Path/Node.hs b/core/src/Streamly/FileSystem/Path/Node.hs
index 68f8b67fa0..5268f040f5 100644
--- a/core/src/Streamly/FileSystem/Path/Node.hs
+++ b/core/src/Streamly/FileSystem/Path/Node.hs
@@ -30,7 +30,7 @@ module Streamly.FileSystem.Path.Node
     , fileE
 
     -- * Operations
-    , append
+    , extend
     )
 where
 
diff --git a/core/src/Streamly/FileSystem/Path/Seg.hs b/core/src/Streamly/FileSystem/Path/Seg.hs
index a4036b4f9e..b53ac1e57f 100644
--- a/core/src/Streamly/FileSystem/Path/Seg.hs
+++ b/core/src/Streamly/FileSystem/Path/Seg.hs
@@ -30,7 +30,7 @@ module Streamly.FileSystem.Path.Seg
     , brE
 
     -- * Operations
-    , append
+    , extend
     )
 where
 
diff --git a/core/src/Streamly/FileSystem/Path/SegNode.hs b/core/src/Streamly/FileSystem/Path/SegNode.hs
index 54d8e705be..8dc9ed5b09 100644
--- a/core/src/Streamly/FileSystem/Path/SegNode.hs
+++ b/core/src/Streamly/FileSystem/Path/SegNode.hs
@@ -30,7 +30,7 @@ module Streamly.FileSystem.Path.SegNode
     , brfileE
 
     -- * Operations
-    , append
+    , extend
     )
 where
 
diff --git a/core/src/Streamly/Internal/FileSystem/DirIO.hs b/core/src/Streamly/Internal/FileSystem/DirIO.hs
index b83ab05164..5b0fc88c56 100644
--- a/core/src/Streamly/Internal/FileSystem/DirIO.hs
+++ b/core/src/Streamly/Internal/FileSystem/DirIO.hs
@@ -314,7 +314,7 @@ toStreamWithBufferOf chunkSize h = AS.concat $ toChunksWithBufferOf chunkSize h
 eitherReaderPaths ::(MonadIO m, MonadCatch m) => (ReadOptions -> ReadOptions) ->
     Unfold m Path (Either Path Path)
 eitherReaderPaths f =
-    let (</>) = Path.append
+    let (</>) = Path.extend
      in UF.mapM2 (\dir -> return . bimap (dir </>) (dir </>)) (eitherReader f)
 
 --
@@ -359,7 +359,7 @@ readEither f = S.unfold (eitherReader f)
 readEitherPaths :: (MonadIO m, MonadCatch m) => (ReadOptions -> ReadOptions) ->
     Path -> Stream m (Either Path Path)
 readEitherPaths f dir =
-    let (</>) = Path.append
+    let (</>) = Path.extend
      in fmap (bimap (dir </>) (dir </>)) $ readEither f dir
 
 #if defined(mingw32_HOST_OS) || defined(__MINGW32__)
diff --git a/core/src/Streamly/Internal/FileSystem/Posix/ReadDir.hsc b/core/src/Streamly/Internal/FileSystem/Posix/ReadDir.hsc
index c28b3931a1..5b03efae1b 100644
--- a/core/src/Streamly/Internal/FileSystem/Posix/ReadDir.hsc
+++ b/core/src/Streamly/Internal/FileSystem/Posix/ReadDir.hsc
@@ -931,7 +931,7 @@ readEitherByteChunksAt confMod (ppath, alldirs) =
                             {-
                             if ndirs > 64
                             then do
-                                let fpath = Path.unsafeAppend ppath curdir
+                                let fpath = Path.unsafeExtend ppath curdir
                                 return $ Yield
                                     (Left (fpath, dirs1))
                                     (ByteChunksAtLoop pfd dirp curdir xs [] 0 mbarr pos1)
@@ -961,7 +961,7 @@ readEitherByteChunksAt confMod (ppath, alldirs) =
                     -- help parallelize more in IO bound case.
                     if ndirs > 0
                     then do
-                        let fpath = Path.unsafeAppend ppath curdir
+                        let fpath = Path.unsafeExtend ppath curdir
                         return $ Yield
                             (Left (fpath, dirs))
                             (ByteChunksAtInit pfd xs mbarr pos)
diff --git a/core/src/Streamly/Internal/FileSystem/PosixPath.hs b/core/src/Streamly/Internal/FileSystem/PosixPath.hs
index 4477f25116..e996a4eb6f 100644
--- a/core/src/Streamly/Internal/FileSystem/PosixPath.hs
+++ b/core/src/Streamly/Internal/FileSystem/PosixPath.hs
@@ -133,17 +133,17 @@ module Streamly.Internal.FileSystem.OS_PATH
     -- * Joining
     , addString
  -- , concat
-    , unsafeAppend -- XXX unsafeExtend
+    , unsafeExtend
 #ifndef IS_WINDOWS
-    , appendCString -- XXX extendByCString
-    , appendCString'
+    , extendByCString
+    , extendByCString'
 #endif
-    , append -- XXX rename to "extend" to emphasize asymmetric nature?
-    , append' -- XXX rename to extendDir, to avoid pinned confusion?
+    , extend
+    , extendDir
     , unsafeJoinPaths
 
     -- * Splitting
-    -- | Note: you can use 'unsafeAppend' as a replacement for the joinDrive
+    -- | Note: you can use 'unsafeExtend' as a replacement for the joinDrive
     -- function in the filepath package.
     , splitRoot
     , splitPath
@@ -299,7 +299,7 @@ hasTrailingSeparator (OS_PATH arr) =
 --
 {-# INLINE addTrailingSeparator #-}
 addTrailingSeparator :: OS_PATH -> OS_PATH
-addTrailingSeparator p = unsafeAppend p sep
+addTrailingSeparator p = unsafeExtend p sep
 
     where
 
@@ -576,10 +576,9 @@ isBranch :: OS_PATH -> Bool
 isBranch = not . isRooted
 
 #ifndef IS_WINDOWS
--- | Like 'append' but does not check if any of the path is empty or if the
--- second path is rooted.
+-- | Like 'extend' but does not check if the second path is rooted.
 --
--- >>> f a b = Path.toString $ Path.unsafeAppend (pack a) (pack b)
+-- >>> f a b = Path.toString $ Path.unsafeExtend (pack a) (pack b)
 --
 -- >>> f "x" "y"
 -- "x/y"
@@ -590,21 +589,19 @@ isBranch = not . isRooted
 -- >>> f "x/" "/y"
 -- "x/y"
 --
-{-# INLINE unsafeAppend #-}
-unsafeAppend :: OS_PATH -> OS_PATH -> OS_PATH
-unsafeAppend (OS_PATH a) (OS_PATH b) =
+{-# INLINE unsafeExtend #-}
+unsafeExtend :: OS_PATH -> OS_PATH -> OS_PATH
+unsafeExtend (OS_PATH a) (OS_PATH b) =
     OS_PATH
         $ Common.unsafeAppend
             Common.OS_NAME (Common.toString Unicode.UNICODE_DECODER) a b
 
--- XXX rename it to extend or combine?
-
--- | Append a OS_PATH to another. Fails if the second path refers to a rooted
--- path. If you want to avoid runtime failure use the typesafe
--- Streamly.FileSystem.OS_PATH.Seg module. Use 'unsafeAppend' to avoid failure
--- if you know it is ok to append the path.
+-- | Extend an OS_PATH by appending another one to it. Fails if the second path
+-- refers to a rooted path. If you want to avoid runtime failure use the
+-- typesafe Streamly.FileSystem.OS_PATH.Seg module. Use 'unsafeExtend' to avoid
+-- failure if you know it is ok to append the path.
 --
--- >>> f a b = Path.toString $ Path.append a b
+-- >>> f a b = Path.toString $ Path.extend a b
 --
 -- >>> f [path|/usr|] [path|bin|]
 -- "/usr/bin"
@@ -613,23 +610,23 @@ unsafeAppend (OS_PATH a) (OS_PATH b) =
 -- >>> fails (f [path|/usr|] [path|/bin|])
 -- True
 --
-append :: OS_PATH -> OS_PATH -> OS_PATH
-append (OS_PATH a) (OS_PATH b) =
+extend :: OS_PATH -> OS_PATH -> OS_PATH
+extend (OS_PATH a) (OS_PATH b) =
     OS_PATH
         $ Common.append
             Common.OS_NAME (Common.toString Unicode.UNICODE_DECODER) a b
 
--- | A stricter version of 'append' which requires the first path to be a
+-- | A stricter version of 'extend' which requires the first path to be a
 -- directory like path i.e. with a trailing separator.
 --
--- >>> f a b = Path.toString $ Path.append' a b
+-- >>> f a b = Path.toString $ Path.extendDir a b
 --
 -- >>> fails $ f [path|/usr|] [path|bin|]
 -- True
 --
-append' ::
+extendDir ::
     OS_PATH -> OS_PATH -> OS_PATH
-append'
+extendDir
     (OS_PATH a) (OS_PATH b) =
     OS_PATH
         $ Common.append'
@@ -640,21 +637,21 @@ append'
 -- XXX add appendCWString for Windows?
 
 #ifndef IS_WINDOWS
--- | Append a separator and a CString to the Array. This is like 'unsafeAppend'
+-- | Append a separator and a CString to the Array. This is like 'unsafeExtend'
 -- but always inserts a separator between the two paths even if the first path
 -- has a trailing separator or second path has a leading separator.
 --
-appendCString :: OS_PATH -> CString -> IO OS_PATH
-appendCString (OS_PATH a) str =
+extendByCString :: OS_PATH -> CString -> IO OS_PATH
+extendByCString (OS_PATH a) str =
     fmap OS_PATH
         $ Common.appendCString
             Common.OS_NAME a str
 
 -- | Like 'appendCString' but creates a pinned path.
 --
-appendCString' ::
+extendByCString' ::
     OS_PATH -> CString -> IO OS_PATH
-appendCString'
+extendByCString'
     (OS_PATH a) str =
     fmap OS_PATH
         $ Common.appendCString'
@@ -684,7 +681,7 @@ unsafeJoinPaths = undefined
 -- Some filepath package equivalent idioms:
 --
 -- >>> splitDrive = Path.splitRoot
--- >>> joinDrive = Path.unsafeAppend
+-- >>> joinDrive = Path.unsafeExtend
 -- >>> takeDrive = fmap fst . Path.splitRoot
 -- >>> dropDrive x = Path.splitRoot x >>= snd
 -- >>> hasDrive = isJust . Path.splitRoot
@@ -844,8 +841,8 @@ splitPath_ (OS_PATH a) = fmap OS_PATH $ Common.splitPath_ Common.OS_NAME a
 -- >>> takeBaseName = fmap Path.dropExtension . takeFileName
 -- >>> dropFileName x = Path.splitFile x >>= fst
 -- >>> takeDirectory x = Path.splitFile x >>= fst
--- >>> replaceFileName p x = fmap (flip Path.append x) (takeDirectory p)
--- >>> replaceDirectory p x = fmap (flip Path.append x) (takeFileName p)
+-- >>> replaceFileName p x = fmap (flip Path.extend x) (takeDirectory p)
+-- >>> replaceDirectory p x = fmap (flip Path.extend x) (takeFileName p)
 --
 -- >>> toList (a,b) = (fmap Path.toString a, Path.toString b)
 -- >>> split = fmap toList . Path.splitFile . pack
diff --git a/core/src/Streamly/Internal/FileSystem/PosixPath/Node.hs b/core/src/Streamly/Internal/FileSystem/PosixPath/Node.hs
index 1aeb025056..d07ac62906 100644
--- a/core/src/Streamly/Internal/FileSystem/PosixPath/Node.hs
+++ b/core/src/Streamly/Internal/FileSystem/PosixPath/Node.hs
@@ -42,7 +42,7 @@ module Streamly.Internal.FileSystem.OS_PATH.Node
     , fileE
 
     -- * Operations
-    , append
+    , extend
     )
 where
 
@@ -147,15 +147,15 @@ file = mkQ fileE
 
 -- | Append a 'Dir' or 'File' path to a 'Dir' path.
 --
--- >>> Path.toString (Node.append [dir|/usr|] [dir|bin|] :: Dir PosixPath)
+-- >>> Path.toString (Node.extend [dir|/usr|] [dir|bin|] :: Dir PosixPath)
 -- "/usr/bin"
--- >>> Path.toString (Node.append [dir|/usr|] [file|bin|] :: File PosixPath)
+-- >>> Path.toString (Node.extend [dir|/usr|] [file|bin|] :: File PosixPath)
 -- "/usr/bin"
 --
 -- Fails if the second path is a specific location and not a path segment.
 --
-{-# INLINE append #-}
-append :: (IsPath OS_PATH (a OS_PATH), IsNode (a OS_PATH)) =>
+{-# INLINE extend #-}
+extend :: (IsPath OS_PATH (a OS_PATH), IsNode (a OS_PATH)) =>
     Dir OS_PATH -> a OS_PATH -> a OS_PATH
-append (Dir a) b =
-    unsafeFromPath $ OsPath.unsafeAppend (toPath a) (toPath b)
+extend (Dir a) b =
+    unsafeFromPath $ OsPath.unsafeExtend (toPath a) (toPath b)
diff --git a/core/src/Streamly/Internal/FileSystem/PosixPath/Seg.hs b/core/src/Streamly/Internal/FileSystem/PosixPath/Seg.hs
index 659fd17c76..3830f2a1b1 100644
--- a/core/src/Streamly/Internal/FileSystem/PosixPath/Seg.hs
+++ b/core/src/Streamly/Internal/FileSystem/PosixPath/Seg.hs
@@ -47,7 +47,7 @@ module Streamly.Internal.FileSystem.OS_PATH.Seg
     , brE
 
     -- * Operations
-    , append
+    , extend
     )
 where
 
@@ -156,15 +156,16 @@ br = mkQ brE
 
 -- | Append a 'Branch' type path to a 'Rooted' path or 'Branch' path.
 --
--- >>> Path.toString (Seg.append [rt|/usr|] [br|bin|] :: Rooted PosixPath)
+-- >>> Path.toString (Seg.extend [rt|/usr|] [br|bin|] :: Rooted PosixPath)
 -- "/usr/bin"
--- >>> Path.toString (Seg.append [br|usr|] [br|bin|] :: Branch PosixPath)
+-- >>> Path.toString (Seg.extend [br|usr|] [br|bin|] :: Branch PosixPath)
 -- "usr/bin"
 --
-{-# INLINE append #-}
-append ::
+{-# INLINE extend #-}
+extend ::
     (
       IsSeg (a OS_PATH)
     , IsPath OS_PATH (a OS_PATH)
     ) => a OS_PATH -> Branch OS_PATH -> a OS_PATH
-append a (Branch c) = unsafeFromPath $ OsPath.unsafeAppend (toPath a) (toPath c)
+extend a (Branch c) =
+    unsafeFromPath $ OsPath.unsafeExtend (toPath a) (toPath c)
diff --git a/core/src/Streamly/Internal/FileSystem/PosixPath/SegNode.hs b/core/src/Streamly/Internal/FileSystem/PosixPath/SegNode.hs
index 3054a682d5..a3124ec22e 100644
--- a/core/src/Streamly/Internal/FileSystem/PosixPath/SegNode.hs
+++ b/core/src/Streamly/Internal/FileSystem/PosixPath/SegNode.hs
@@ -1,5 +1,5 @@
 {-# LANGUAGE TemplateHaskell #-}
--- For constraints on "append"
+-- For constraints on "extend"
 {-# OPTIONS_GHC -Wno-redundant-constraints #-}
 {-# OPTIONS_GHC -Wno-orphans #-}
 
@@ -40,7 +40,7 @@ module Streamly.Internal.FileSystem.OS_PATH.SegNode
     , brfileE
 
     -- * Operations
-    , append
+    , extend
     )
 where
 
@@ -245,39 +245,39 @@ brfile = mkQ brfileE
 -- If the second path does not have 'File' or 'Dir' information then the return
 -- type too cannot have it.
 --
--- >> Path.toString (SegNode.append [rtdir|/usr|] [br|bin|] :: Rooted PosixPath)
+-- >> Path.toString (SegNode.extend [rtdir|/usr|] [br|bin|] :: Rooted PosixPath)
 -- "/usr/bin"
--- >> Path.toString (SegNode.append [brdir|usr|] [br|bin|] :: Branch PosixPath)
+-- >> Path.toString (SegNode.extend [brdir|usr|] [br|bin|] :: Branch PosixPath)
 -- "usr/bin"
 --
--- >> Path.toString (SegNode.append [rt|/usr|] [br|bin|] :: Rooted PosixPath)
+-- >> Path.toString (SegNode.extend [rt|/usr|] [br|bin|] :: Rooted PosixPath)
 -- "/usr/bin"
--- >> Path.toString (SegNode.append [br|usr|] [br|bin|] :: Branch PosixPath)
+-- >> Path.toString (SegNode.extend [br|usr|] [br|bin|] :: Branch PosixPath)
 -- "usr/bin"
 --
 -- If the second path has 'File' or 'Dir' information then the return type
 -- also has it.
 --
--- >> Path.toString (SegNode.append [rt|/usr|] [brdir|bin|] :: Rooted (Dir PosixPath))
+-- >> Path.toString (SegNode.extend [rt|/usr|] [brdir|bin|] :: Rooted (Dir PosixPath))
 -- "/usr/bin"
--- >> Path.toString (SegNode.append [rt|/usr|] [brfile|bin|] :: Rooted (File PosixPath))
+-- >> Path.toString (SegNode.extend [rt|/usr|] [brfile|bin|] :: Rooted (File PosixPath))
 -- "/usr/bin"
--- >> Path.toString (SegNode.append [br|usr|] [brdir|bin|] :: Branch (Dir PosixPath))
+-- >> Path.toString (SegNode.extend [br|usr|] [brdir|bin|] :: Branch (Dir PosixPath))
 -- "usr/bin"
--- >> Path.toString (SegNode.append [br|usr|] [brfile|bin|] :: Branch (File PosixPath))
+-- >> Path.toString (SegNode.extend [br|usr|] [brfile|bin|] :: Branch (File PosixPath))
 -- "usr/bin"
 --
 -- Type error cases:
 --
--- >> SegNode.append [dir|/usr|] [br|bin|] -- first arg must be Rooted/Branch
--- >> SegNode.append [file|/usr|] [br|bin|] -- first arg must be Rooted/Branch
--- >> SegNode.append [rtfile|/usr|] [br|bin|] -- first arg must be a dir
--- >> SegNode.append [rt|/usr|] [rt|/bin|] -- second arg must be seg
--- >> SegNode.append [rt|/usr|] [dir|bin|] -- second arg must be seg
--- >> SegNode.append [rt|/usr|] [file|bin|] -- second arg must be seg
+-- >> SegNode.extend [dir|/usr|] [br|bin|] -- first arg must be Rooted/Branch
+-- >> SegNode.extend [file|/usr|] [br|bin|] -- first arg must be Rooted/Branch
+-- >> SegNode.extend [rtfile|/usr|] [br|bin|] -- first arg must be a dir
+-- >> SegNode.extend [rt|/usr|] [rt|/bin|] -- second arg must be seg
+-- >> SegNode.extend [rt|/usr|] [dir|bin|] -- second arg must be seg
+-- >> SegNode.extend [rt|/usr|] [file|bin|] -- second arg must be seg
 --
-{-# INLINE append #-}
-append ::
+{-# INLINE extend #-}
+extend ::
     (
       IsSeg (a b)
     , HasDir (a b)
@@ -285,26 +285,26 @@ append ::
     , IsPath OS_PATH c
     , IsPath OS_PATH (a c)
     ) => a b -> Branch c -> a c
-append a (Branch c) = unsafeFromPath $ OS_NAME.unsafeAppend (toPath a) (toPath c)
+extend a (Branch c) = unsafeFromPath $ OS_NAME.unsafeExtend (toPath a) (toPath c)
 -}
 
 -- | Append a branch type path to a directory.
 --
--- >>> Path.toString (SegNode.append [rtdir|/usr|] [brdir|bin|] :: Rooted (Dir PosixPath))
+-- >>> Path.toString (SegNode.extend [rtdir|/usr|] [brdir|bin|] :: Rooted (Dir PosixPath))
 -- "/usr/bin"
--- >>> Path.toString (SegNode.append [rtdir|/usr|] [brfile|bin|] :: Rooted (File PosixPath))
+-- >>> Path.toString (SegNode.extend [rtdir|/usr|] [brfile|bin|] :: Rooted (File PosixPath))
 -- "/usr/bin"
--- >>> Path.toString (SegNode.append [brdir|usr|] [brdir|bin|] :: Branch (Dir PosixPath))
+-- >>> Path.toString (SegNode.extend [brdir|usr|] [brdir|bin|] :: Branch (Dir PosixPath))
 -- "usr/bin"
--- >>> Path.toString (SegNode.append [brdir|usr|] [brfile|bin|] :: Branch (File PosixPath))
+-- >>> Path.toString (SegNode.extend [brdir|usr|] [brfile|bin|] :: Branch (File PosixPath))
 -- "usr/bin"
 --
-{-# INLINE append #-}
-append ::
+{-# INLINE extend #-}
+extend ::
     (
       IsPath OS_PATH (a (Dir OS_PATH))
     , IsPath OS_PATH (b OS_PATH)
     , IsPath OS_PATH (a (b OS_PATH))
     ) => a (Dir OS_PATH) -> Branch (b OS_PATH) -> a (b OS_PATH)
-append p1 (Branch p2) =
-    unsafeFromPath $ OsPath.unsafeAppend (toPath p1) (toPath p2)
+extend p1 (Branch p2) =
+    unsafeFromPath $ OsPath.unsafeExtend (toPath p1) (toPath p2)
diff --git a/core/src/Streamly/Internal/FileSystem/WindowsPath.hs b/core/src/Streamly/Internal/FileSystem/WindowsPath.hs
index 139da10619..05e8d00ddc 100644
--- a/core/src/Streamly/Internal/FileSystem/WindowsPath.hs
+++ b/core/src/Streamly/Internal/FileSystem/WindowsPath.hs
@@ -219,10 +219,10 @@ readRaw = fromJust . fromChunk . read
 isRooted :: OS_PATH -> Bool
 isRooted (OS_PATH arr) = Common.isRooted Common.OS_NAME arr
 
--- | Like 'append' but does not check if any of the path is empty or if the
+-- | Like 'extend' but does not check if any of the path is empty or if the
 -- second path is rooted.
 --
--- >>> f a b = Path.toString $ Path.unsafeAppend (pack a) (pack b)
+-- >>> f a b = Path.toString $ Path.unsafeExtend (pack a) (pack b)
 --
 -- >>> f "x" "y"
 -- "x\\y"
@@ -233,9 +233,9 @@ isRooted (OS_PATH arr) = Common.isRooted Common.OS_NAME arr
 -- >>> f "x/" "/y"
 -- "x/y"
 --
--- Note "c:" and "/x" are both rooted paths, therefore, 'append' cannot be used
+-- Note "c:" and "/x" are both rooted paths, therefore, 'extend' cannot be used
 -- to join them. Similarly for joining "//x/" and "/y". For these cases use
--- 'unsafeAppend'. 'unsafeAppend' can be used as a replacement for the
+-- 'unsafeExtend'. 'unsafeExtend' can be used as a replacement for the
 -- joinDrive function from the filepath package.
 --
 -- >>> f "c:" "/x"
@@ -243,27 +243,27 @@ isRooted (OS_PATH arr) = Common.isRooted Common.OS_NAME arr
 -- >>> f "//x/" "/y"
 -- "//x/y"
 --
-{-# INLINE unsafeAppend #-}
-unsafeAppend :: OS_PATH -> OS_PATH -> OS_PATH
-unsafeAppend (OS_PATH a) (OS_PATH b) =
+{-# INLINE unsafeExtend #-}
+unsafeExtend :: OS_PATH -> OS_PATH -> OS_PATH
+unsafeExtend (OS_PATH a) (OS_PATH b) =
     OS_PATH
         $ Common.unsafeAppend
             Common.OS_NAME (Common.toString Unicode.UNICODE_DECODER) a b
 
 -- | Append a OS_PATH to another. Fails if the second path refers to a rooted
 -- path. If you want to avoid runtime failure use the typesafe
--- Streamly.FileSystem.OS_PATH.Seg module. Use 'unsafeAppend' to avoid failure
+-- Streamly.FileSystem.OS_PATH.Seg module. Use 'unsafeExtend' to avoid failure
 -- if you know it is ok to append the path.
 --
 -- Usually, append joins two paths using a separator between the paths. On
 -- Windows, joining a drive "c:" with path "x" does not add a separator between
 -- the two because "c:x" is different from "c:/x".
 --
--- Note "c:" and "/x" are both rooted paths, therefore, append cannot be used
+-- Note "c:" and "/x" are both rooted paths, therefore, 'extend' cannot be used
 -- to join them. Similarly for joining "//x/" and "/y". For these cases use
--- 'unsafeAppend'.
+-- 'unsafeExtend'.
 --
--- >>> f a b = Path.toString $ Path.append a b
+-- >>> f a b = Path.toString $ Path.extend a b
 --
 -- >>> f [path|x|] [path|y|]
 -- "x\\y"
@@ -284,23 +284,23 @@ unsafeAppend (OS_PATH a) (OS_PATH b) =
 -- True
 -- >>> fails $ f [path|//x/|] [path|/y|]
 -- True
-append :: OS_PATH -> OS_PATH -> OS_PATH
-append (OS_PATH a) (OS_PATH b) =
+extend :: OS_PATH -> OS_PATH -> OS_PATH
+extend (OS_PATH a) (OS_PATH b) =
     OS_PATH
         $ Common.append
             Common.OS_NAME (Common.toString Unicode.UNICODE_DECODER) a b
 
--- | A stricter version of 'append' which requires the first path to be a
+-- | A stricter version of 'extend' which requires the first path to be a
 -- directory like path i.e. with a trailing separator.
 --
--- >>> f a b = Path.toString $ Path.append' a b
+-- >>> f a b = Path.toString $ Path.extendDir a b
 --
 -- >>> fails $ f [path|x|] [path|y|]
 -- True
 --
-append' ::
+extendDir ::
     OS_PATH -> OS_PATH -> OS_PATH
-append'
+extendDir
     (OS_PATH a) (OS_PATH b) =
     OS_PATH
         $ Common.append'