module Exercise04 where

{-WETT-}

tag:: String -> Bool -> (String,String,Bool)
tag [] _ = (" "," ",False)
tag ('>':ss) _  = (" ",ss,True)
tag (' ':ss) _ = tag ss False
tag (s:ss) b    | b = (s:xs,ys,br) 
                | otherwise = (" "," ",False)
                    where (xs,ys,br) = tag ss b


xml:: String -> [String] -> Bool
xml [] [] = False
xml [] [""] = True
xml [] (_:_) = False
xml ('>':_) _ = False
xml ('<':ss) (x:xs) = if t == '/' then x == ts && valid && xml r xs else valid && xml r ((t:ts):x:xs)
                    where (t:ts,r,valid) = tag ss True
xml (_:ss) xs   = xml ss xs
                 



xmlLight :: String -> Bool
xmlLight s = xml s [""] 
{-TTEW-}