Add signatures for splitFirst and splitLast

Author: harendra-kumar

core/src/Streamly/Internal/FileSystem/Path/Common.hs

@@ -718,15 +718,15 @@ splitPath = splitPathUsing True
 -- /Unimplemented/
 {-# INLINE splitHead #-}
 splitHead :: -- (Unbox a, Integral a) =>
-    OS -> Array a -> (Array a, Array a)
+    OS -> Array a -> (Array a, Maybe (Array a))
 splitHead _os _arr = undefined
 
 -- | Split the last non-empty path component.
 --
 -- /Unimplemented/
 {-# INLINE splitTail #-}
 splitTail :: -- (Unbox a, Integral a) =>
-    OS -> Array a -> (Array a, Array a)
+    OS -> Array a -> (Maybe (Array a), Array a)
 splitTail _os _arr = undefined
 
 ------------------------------------------------------------------------------

core/src/Streamly/Internal/FileSystem/PosixPath.hs

@@ -150,6 +150,9 @@ module Streamly.Internal.FileSystem.OS_PATH
     , splitPath_
     , splitFile
 
+    , splitFirst
+    , splitLast
+
     , splitExtension
     , dropExtension
     , addExtension
@@ -886,6 +889,25 @@ splitFile :: OS_PATH -> Maybe (Maybe OS_PATH, OS_PATH)
 splitFile (OS_PATH a) =
     fmap (bimap (fmap OS_PATH) OS_PATH) $ Common.splitFile Common.OS_NAME a
 
+-- | Split the path into the first component and rest of the path. Treats the
+-- entire root or share name, if present, as the first component.
+--
+-- /Unimplemented/
+splitFirst :: OS_PATH -> (OS_PATH, Maybe OS_PATH)
+splitFirst (OS_PATH a) =
+    bimap OS_PATH (fmap OS_PATH) $ Common.splitHead Common.OS_NAME a
+
+-- | Split the path into the last component and rest of the path. Treats the
+-- entire root or share name, if present, as the first component.
+--
+-- >>> basename = snd . Path.splitLast -- Posix basename
+-- >>> dirname = fst . Path.splitLast -- Posix dirname
+--
+-- /Unimplemented/
+splitLast :: OS_PATH -> (Maybe OS_PATH, OS_PATH)
+splitLast (OS_PATH a) =
+    bimap (fmap OS_PATH) OS_PATH $ Common.splitTail Common.OS_NAME a
+
 #ifndef IS_WINDOWS
 -- Note: In the cases of "x.y." and "x.y.." we return no extension rather
 -- than ".y." or ".y.." as extensions. That is they considered to have no