particiona :: (Ord t)=> [t] -> ([t], [t])
particiona [] = ([], [])
particiona [a] = ([a],[])
particiona (a:b:c) = ([a]++as, ([b]++bs))
 where (as, bs) = particiona c

compara :: (Ord t)=> [t] -> [t] -> [t]
compara [] b = b
compara a [] = a
compara (a:as) (b:bs)|a<b = [a] ++ (compara as ([b]++bs))
                     |otherwise = [b] ++ (compara ([a]++as) bs)

mergesort :: (Ord t)=> [t] -> [t]
mergesort [] = []
mergesort a = compara (mergesort (fst(particiona a)))  (mergesort (snd(particiona a)))