module Exercise_7 where

import Data.List
import Data.Tuple
import Data.Function

{-WETT-}
trancl :: Eq a => [(Integer,(a,a))] -> [(Integer,(a,a))]
trancl xs = head  $ dropWhile (\x-> f x /= x)  $  iterate f xs
 where f ys  = nubBy ((==) `on` snd ) $ sortBy (compare `on` fst) $ ys ++ [(p+q,(x,t))|(p,(x,y))<-xs,(q,(z,t))<-ys,y==z]
{-TTEW-}