+ 0 y y + s x y s + x y ++ nil ys ys ++ : x xs ys : x ++ xs ys sum : x nil : x nil sum : x : y xs sum : + x y xs sum ++ xs : x : y ys sum ++ xs sum : x : y ys - x 0 x - 0 s y 0 - s x s y - x y quot 0 s y 0 quot s x s y s quot - x y s y length nil 0 length : x xs s length xs hd : x xs x avg xs quot hd sum xs length xs + 2 0 0 s 1 ++ 2 nil 0 : 2 sum 1 - 2 quot 2 length 1 hd 1 avg 1 FULL ./TRS/various/10.trs