Don't collapse empty lines in 'lines'

libs/base/Data/Strings.idr

@@ -71,10 +71,13 @@ unwords = pack . unwords' . map unpack
 ||| lines' (unpack "\rA BC\nD\r\nE\n")
 ||| ```
 lines' : List Char -> List (List Char)
-lines' s = case dropWhile isNL s of
-            [] => []
-            s' => let (w, s'') = break isNL s'
-                  in w :: lines' s''
+lines' [] = []
+lines' s  = case break isNL s of
+              (l, s') => l :: case s' of
+                                []       => []
+                                _ :: s'' => lines' (assert_smaller s s'')
+
+
 
 ||| Splits a string into a list of newline separated strings.
 |||