Bring type of reverseIter in line with iter

Author: Bodigrim

src/Data/Text.hs

@@ -1163,7 +1163,7 @@ takeWhileEnd p t@(Text arr off len) = loop (len-1) len
  where loop !i !l | l <= 0 = t
  | p c = loop (i+d) (l+d)
  | otherwise = text arr (off+l) (len-l)
- where (c,d)  = reverseIter t i
+ where Iter c d = reverseIter t i
 {-# INLINE [1] takeWhileEnd #-}
 
 -- | /O(n)/ 'dropWhile' @p@ @t@ returns the suffix remaining after
@@ -1189,7 +1189,7 @@ dropWhileEnd p t@(Text arr off len) = loop (len-1) len
  where loop !i !l | l <= 0 = empty
  | p c = loop (i+d) (l+d)
  | otherwise = Text arr off l
- where (c,d)  = reverseIter t i
+ where Iter c d = reverseIter t i
 {-# INLINE [1] dropWhileEnd #-}
 
 -- | /O(n)/ 'dropAround' @p@ @t@ returns the substring remaining after

src/Data/Text/Unsafe.hs

@@ -89,10 +89,10 @@ iter_ (Text arr off _len) i | m < 0xD800 || m > 0xDBFF = 1
 -- | /O(1)/ Iterate one step backwards through a UTF-16 array,
 -- returning the current character and the delta to add (i.e. a
 -- negative number) to give the next offset to iterate at.
-reverseIter :: Text -> Int -> (Char,Int)
+reverseIter :: Text -> Int ->  Iter
 reverseIter (Text arr off _len) i
- | m < 0xDC00 || m > 0xDFFF = (unsafeChr m, -1)
- | otherwise = (chr2 n m, -2)
+ | m < 0xDC00 || m > 0xDFFF = Iter (unsafeChr m) (-1)
+ | otherwise = Iter (chr2 n m) (-2)
  where m = A.unsafeIndex arr j
  n = A.unsafeIndex arr k
  j = off + i